7.62 NATO vs .308 Winchester Ammo, What’s The Difference?

Gun nut, Tom McHale, risks a fight to explain the subtle nuances between 7.62 NATO vs .308 Winchester Ammunition.

Can you shoot .308 ammo in a 7.62 rifle? Or is it the other way around?
Can you shoot .308 ammo in a 7.62 rifle? Or is it the other way around?

Tom McHale

USA –-(Ammoland.com)- If you want to start a good bar fight, ask about a saloon full of gun people about the differences between .308 Winchester and 7.62x51mm NATO. We’re going to dive into the fray with a simplified and practical explanation. Ready?

  • They are different.
  • They aren’t different.
  • They might be different.

OK, so that was a bit of a wise guy response, but those statements are all quite true. Don’t worry, we’ll explain further. However, we’re going to try to do that in such a way that you don’t want to bash your own brains out by having to read about the nuances of things like piezo transducers.

Let’s look at a few categories of comparison, then we’ll sum things up.

7.62 NATO vs .308 Winchester – History

Doing the 1940s and early 1950s, military rocket surgeons wanted to improve the effectiveness of the M1 Garand rifle and its .30-06 cartridge. One contender, more suitable for higher capacity box magazines was a modified .300 Savage design called the T65. While specs varied throughout development, it ended up as the earliest iteration of the 7.62x51mm NATO. But, as usual, the commercial market was more nimble, and Winchester launched the .308 Winchester in 1952.

It took the government until 1957 to have a cartridge and rifle hitting the barracks with similar specs.

7.62 vs .308 – Pressure

Here’s where some of the confusion comes into the picture. Maximum pressure numbers thrown around for the two calibers are often shown as 50,000 “psi” for 7.62 and 62,000 psi for .308. At first glance, that appears to be a big difference and a potential reason why folks might consider it unsafe to fire a “higher pressure” commercial .308 cartridge in a rifle built for 7.62x51mm NATO.

While commercial .308 ammo may have slightly higher pressure than 7.62x51mm NATO, it's really the brass and chambers that are the issues to understand.
While commercial .308 ammo may have slightly higher pressure than 7.62x51mm NATO, it's really the brass and chambers that are the issues to understand.

As with most things, the devil is in the details. I put that 50,000 “psi” number in quotes because it’s wrong, at least when shown with a pounds per square inch label at the end. That 50,000 number is actually an accurate representation of copper units of pressure or CUP. A far less precise way to measure pressure, the method literally relies on looking at how much little copper disks compress when you fire the gun. While there isn’t a consistent mathematical formula that equates CUP to pounds per square inch (PSI) across the board, the difference in this specific case is somewhere around 8,000. In other words, the maximum pressure for 7.62x51mm NATO is about 58,000 psi – not all that far from the 62,000 figure for commercial .308 Winchester.

As both loads are routinely proof tested at far higher levels, this 4,000 isn't a difference that's going to alter the trajectory of Michael Moore's daily Krispy Kreme run.

7.62 NATO vs .308 Win – Case thickness

Measuring the thickness of cartridge cases is kind of a pain, especially since I tend to mash them all up when trying to cut them in half with my Dremel tool. So, I took the shortcut to illustrate the difference. From my big bucket of .308 / 7.62 brass, I selected some representative samples of both commercial .308 Winchester and 7.62x51mm NATO brass and weighed them. I picked several of each and averaged the weights. I didn’t measure the cases because they’ve been fired, so that won’t tell me much other than the general size of the chamber from which they went bang.

  • Hornady .308: 169.6 grains
  • Winchester .308: 163.3 grains
  • Lake City 7.62x51mm NATO: 183.5 grains

That’s a significant difference! Thicker walls combined with similar exterior dimensions means less powder capacity and a lower “top end” and all else the same, lower pressure and velocity.

The thicker brass of 7.62 cases is a significant factor for the reason we'll discuss next.

7.62 NATO vs .308 Winchester – Headspace

Last but not least we get to the real difference. Military rifles for 7.62x51mm NATO can, and usually do, have longer chambers. In things like machine guns powered by ammo made all over the world, there’s got to be some slack for reliable feeding and operation with all that violence going on during the feeding and ejection process. The solution is to make the chamber headspace a bit longer. If you’re not familiar with headspace, think of it as the distance from the bolt face to the point in the chamber that stops forward motion of the cartridge case. If chamber headspace is too long for a cartridge, it will float back and forth in the chamber. If headspace is too small, the bolt will not close properly or will require excess force to close.

How much different is the headspace? The .308 Winchester chamber headspace is between 1.630 and 1.6340 inches. The 7.62x51mm NATO is between 1.6355 and 1.6405 inches. While the published numbers show about six-thousandths of an inch difference, it’s not unusual for the headspace in a surplus 7.62 rifle to be 10 or even 15 thousandths longer than that of a commercial .308. That doesn’t sound like a big deal, right up to the point where you fire thinner commercial brass in a long-chambered rifle. The brass will stretch, possibly enough to contribute to a dangerous case rupture. Doing the same thing with thicker military brass is no big deal and the way the system was designed. Thicker brass can handle some extra stretching into a longer chamber throat, so it's no big deal.

The solution to the question is to know your rifle and what its headspace really is. Only then will you know if its safe to shoot commercial .308 Winchester ammo in a 7.62 chamber.

Figuring out if your headspace is safe is a fairly straightforward deal. You can order a set of .308 Winchester Go / No-Go headspace gauges. After removing extractors and/or ejectors as appropriate in order to remove all sources of tension, use the gauges to check the chamber size. The bolt should close easily on a Go gauge and not close on a No-Go gauge. A third type, a Field Gauge checks the maximum published chamber size. With some 7.62 rifles, you might find that the bolt closes on the No-Go gauge. As long as the bolt won't close on the Field gauge, you're still within maximum published limits.

The net-net-net

Technically speaking, in terms of specifications, there are differences, but mainly in the chambers of rifles designed to fire each cartridge. 7.62 brass is a bit thicker, and commercial .308 is sometimes loaded to slightly higher pressure, but other than that, the cartridges themselves are pretty much the same.

If you want to be ultra safe and conservative, fire only 7.62x51m NATO in 7.62 chambered rifles and .308 Winchester in .308 rifles.

Next on the “risk” spectrum is the scenarios of using 7.62x51mm NATO ammo in a .308 chamber. In theory, you might run across ammo that’s particularly long. Ammo might not chamber at all or might require undue pressure to the chamber. That could result in dangerously high pressure. In reality, that would be really unusual. While 7.62 ammo could be significantly longer, that's a pretty rare thing, at least to a significant level, so most people don’t consider it a big deal to use 7.62 ammo in a .308 chambered rifle.

Where you need to be careful is using .308 Winchester commercial ammo in a 7.62x51mm NATO chambered rifle.

While most modern 7.62 chambers are probably fine as they tend to be cut closer to .308 dimensions, it’s always safest to know exactly what you have in terms of headspace. If your rifle has long headspace, stick to 7.62 NATO ammo – don’t use commercial .308.


Tom McHale is the author of the Insanely Practical Guides book series that guides new and experienced shooters alike in a fun, approachable, and practical way. His books are available in print and eBook format on Amazon. You can also find him on Google+, Facebook, Twitter and Pinterest.

  • 86 thoughts on “7.62 NATO vs .308 Winchester Ammo, What’s The Difference?

    1. Several ammunition manufacturers have ammo marked 308/7.62×51. Apparently they need to be corrected by Gregory, according to him, you can’t do that. I have read this thread over and found nowhere where he shows any researched facts and figures. Guess if you belong to a range and can shoot makes you know all and can disrespect and insult anyone who has a legitimate question. Glad he is not at my range. All I see is Gregory being an ass.

    2. I just bought a PSA PA-10 and it says 308 on the barrel. That’s great except I reload and I buy once fired 7.62×51 brass that has been cleaned, resized, and primmer pockets reamed. I’m assuming that reloading them to 308 spec’s should work?

      1. On January 28, 1986, the NASA shuttle orbiter mission STS-51-L and the tenth flight of Space Shuttle Challenger broke apart 73 seconds into its flight, killing all seven crew members.

        I’m relation, that space shuttle, “should have worked”? Then again if you want to buy a brand new Mercedes then run to Wal-Mart and swap out the tires, for whatever I’m-godly reason? Have at it! Personally? I would rather spend the extra 12 cents per round that you might be saving and buy factory fresh ammo. But hey? I’m funny that way!

      2. After sizing the brass, the 7.62 will still have thicker walls, meaning less space for powder to expand, meaning potentially greater pressures. Unless you have the tools and safety equipment necessary for measuring pressure, I’d recommend using the ammo marked on the barrel.

      3. Ignore Mr. Romeu. The answer is yes. But remember to stay on the low side and work up. The brass is thicker so pressures rise a little quicker. Your rifle is rated for 62,000 PSI. Stay at about 56,000 PSI or 47,000 CUP and you’re all right when using the .308 data. Start about 10% below the maximum load in the load manual and work up. Check your brass for signs of scuffing on the face, and primer flattening. Measure each of your test cases with a caliper and compare them with once fired commercial brass. Work up in half grain intervals using 10 rounds for each load. Use commercial brass fired only in your rifle for the comparison. The brass has exactly the same outside diameter and dimensions as the .308 Winchester, and re-sizes to exactly the same dimensions.
        I would caution you to run it through a small base die or a full length resizing die just to make sure it will chamber, as it was probably fired in an M240 mg, but that’s about all you need to do to use the brass. The M 240 causes the brass to stretch slightly due to the rapid cyclic rate of fire, which most gunners set at around 900 rounds per minute because the lower cyclic rates let the gas port carbon up, jamming the gun. But all semi-auto and automatic rifles stretch brass somewhat due to the fact that chamber pressure is still present during ejection. That includes civilian and military semi-or automatic weapons. I use the US 7.62 in several rifles. The thing to remember is that even if the brass is out of spec, the full-length die will bring it back into proper specs. And you need to full length resize if you’re going to use .308 / 7.62 in several rifles. Also, try to stay with US brass. The make-up of the metal will be within safe specs for your rifle. German brass, Sellier % Belou, IMI, and Privi-Partizan brass is ok, too. When your tests are complete, stay with the brass you used in the test and you will be as safe as with commercial loads. Use once-fired brass only for each 10 rounds, and make sure all rounds have the same headstamp. If you change brass or mix brass brands, pressures will be different and inconsistent. Loading 40 to 50 rounds should do you.
        Stay with the same powder bullet type/weight and primer brand throughout the test, too, as changing any of these components will change the pressure curve. Once you have a baseline for pressure and accuracy for one brand of brass, you can then do the same for other brass or components, but by going about 1 grain of powder down from your original load data and working up. Same for changing other components. If you follow these steps, not only can you use the brass safely, but the Lake City brass and the IMI brass will produce some of the most accurate ammunition you can fire.
        Now for my credentials: I am retired US Army Infantry. I was a sniper on the DMZ in 1988 (ROK), I was an armorer in the 25th Infantry for three years. I have shot expert with All the weapons the army had during my active duty. I trained soldiers in rifle marksmanship, basic and advanced, pistol marksmanship (m-9 and 1911A1) basic and advanced, M249, M60, M240 A/B/C, M2 Cal 50 HB Browning MG basic and advanced, conducted range maintenance and 2nd level armorer’s maintenance on all of these weapons, cleared and repaired their malfunctions in the field, and repaired them when parts were available in the unit arms rooms. I’ve also repaired and rebuilt the 25mm chain gun feed and bolt mechanisms on the M2 Bradley Fighting Vehicle. I am also an avid reloader, and have been reloading since I was 14 years old. I started reloading for my Dad’s 30-06 around 1965. I currently reload for the 223/5.56, 6mm Remington, 25-06, 270 Win., 308/7.62×51, 30-06, .300 Winchester Magnum, .35 Whelen, 45-70 Govt., 357 mag/38 special, 44 special/44Mag, 45APC and 50/90 Sharps. The new Lee manual, the new Speer manual, and the new Lyman manual will give you good guidance for working up loads. The Hodgdon manual will give you recipes for Hodgden, IMR and Winchester powders for about everything you will want to reload. Get them and read/follow the instructions. They will keep you reloading safely. Have fun, shoot straight and stay safe. Hope this helps.
        Elton P. Green SSG, USA, INF. Ret.

    3. No, Greg does not live overseas. He belongs to a rifle club and knows what he’s talking about, and also, he is an excellent marksman ‼️

    4. Gregory was very helpful on providing you all on some facts and figures that took some time to research. I appreciate the time and effort it took. There is always gonna be several out there that do not agree on your views and research, Why i dont know, like viper said use the ammo that is recommended for that weapon and be safe brothers. army vet.

    5. Gregory Romeu, you seem to be a “internet troll” that pounces on anyone and anything that can make you feel smart in your own eyes, I’m here to help you, you are being a jerk, your life is missing something don’t sit at home and worship yourself. Back away from the computer and go look in the mirror. We hate your attitude here. Please try to educate yourself in basic kindness, maybe read the Bible. We would gladly welcome you if you would try to be a bit nicer. You do have a good heart inside you, feed it please. People will respect you.
      Sincerely Your friend,

      1. Obviously you have no understanding or idea as to what a TROLL actually is? Me? Not are troll by any means, I just loathe ignorance and stupidity, especially when the ANSWERS are bore right into the barrels of the firearms these people are in posession of. If you took the time to read deep into the text of those I responded to you would find most should not possess a firearm.

        There is no place for niceties once a trigger is pulled. And you with a name like, “Cracker”?

    6. “LONG 7.62 RARE”? Depends on the source! ESPECIALLY when buying milsurp ammo. I recently bought close to 500rds of belt pieces from a guy that bought them at an auction that I disintegrated by hand and I’m averaging about 30% that’s too long for my magazine.

      Sometimes “military surplus” is code for “military JUNK”!

      I should’ve known better because I have inside knowledge! For about a year I was assigned a post as Assistant Barracks Mgr. Anytime we had worn out or just plain UNSERVICEABLE furniture it was sent to DRMO (Defense Reutilization and Marketing Office). They scrap or resell that stuff to the highest bidder. If someone bids $500 for 10,000 rounds of reject ammo and that’s the highest bid, there ya go!

    7. Good read but one big mistake. All else being equal a thicker case will have higher pressure. Less volume and the same amount of powder equals higher pressure.

      1. Buy wouldn’t a 308 case with a heavier bullet, with more powder to achieve longer and more effective ballistic performance generate higher pressures?

    8. Good read but there’s a critical mistake. All else being the same, a thicker case will generate a higher pressure. A smaller volume with the equal amount of powder equals higher pressure. Is a standard .308 a compressed load? That would depend on the powder density and I’m sure all .308 are not compressed.
      From Berger on COAL and Bullet seating depth. “The primary effect of loading a cartridge long is that it leaves more internal volume inside the cartridge. This extra internal volume has a well-known effect; for a given powder charge, there will be less pressure and less velocity produced because of the extra empty space.”
      The converse is true as well “less volume, same powder, equal higher pressure.” Again this assumes non-compressed loads.

      1. The only thing I can say is that you may be overlooking quite a bit in that little phrase “all else being the same”. Most hand loading data from Hornady, Nosler, and Winchester state that there are two different sets of loads, one for .308 and one for 7.62, and the reason given is the lesser room inside the 7.62. There is no doubt at all that 7.62 is done to a slightly lower pressure. It is not “same powder”.

        1. You didn’t read what I wrote, I know 7.62 and .308 are different in nearly the same way as .223 and 5.56 are, except 5.56 is the one with higher pressure. Quote from article “Thicker walls combined with similar exterior dimensions means less powder capacity and a lower “top end” and all else the same, lower pressure and velocity.” This is incorrect, misleading and possibly dangerous.
          A smaller case all else being the same, i.e. a .308 load in a Lake City 7.62 case vs. a .308 case, with the same bullet, same weight and type of powder, same primer the thicker 7.62 case will result in less volume and higher pressure and velocity. This is a scientific fact based on Boyle’s Law. Bullet seating depth will affect pressure as well, seated deeper equal less case volume and more pressure and velocity.

          1. Well, you are entirely entitled to your understanding of my reply. But I quoted you. My statement is concerned with your insistence that you would use the same powder charge on the 7.62 as you would .308. IF you did this, the pressure would be higher, yes. BUT loading specs from Hornady and the like state NOT to do this.

    9. Windham Weaponry SRC R16SFST-308
      Semi Automatic Rifle
      .308 Winchester and Accepts 7.62mm NATO
      16.5″ Medium Profile Barrel
      4150m Chrome Moly Vanadium 11595E Steel Barrel
      I am looking at this rifle..you will note it says it will accept 7.62 NATO ammo is it safe to fire it then.
      From the article a bove you seem to say so. Being that I have served and can get NATO 7.62 I would like a definite answer, if you please

      1. Tim, 1) A blind monkey smoking a crack-pipe can get 7.62 NATO ammo. 2) If you served, in WHAT did you serve? And if so, then WHY didn’t teach you to put into the weapon that which is marked on the weapon? You wouldn’t put a,5.56 ball round in that chamber, would you? In other words, if it SAYS “7.62 NATO” on the barrel, then OBVIOUSLY you would use, “7.62 NATO” ammo.

        Now, go ahead and explain to us all the special privledges YOU have in getting 7.62 NATO ammo, just because you served?

        1. @Gregory Romeu
          Jesus, you are a DICK!!!!! Tim was just asking a question. No reason to be a spiteful prick about it!!!
          It’s people like YOU that are ruining the world for the “good people”!!!!

        2. Gregory… Perhaps he is not in the US? Maybe he lives in the EU or somewhere else where firearms and ammo are severely restricted… Every think about that possibility genius?

        3. Gregory.
          let me ask you a question.
          i have a FN/FAL in 7.62 nato and that’s what i shoot in it.
          but i also have a Savage Model 99 that says 308 caliber.
          so i’m assuming i wouldn’t be able to shoot the 7.62 in my Savage due to the chamber not being as long as my FN/FAL.
          is this right?
          and thanks for any answer.
          and i served as a Marine from 1960 to 1971.
          and yes, a Vietnam vet.

      2. The only definitive answer is to have a professional gunsmith determine the exact head space of the rifle. As mentioned in the article, a rifle that is chambered for .308 tends to have a headspace that is tighter, and here you want to think smaller. A rifle that has been chambered for 7.62 USUALLY has a longer headspace due to the multitude of different factories making this ammo around the world. The 7.62 NATO round has a thicker wall and is made to have a lower pressure. .308 is made with a thinner wall and higher pressure. So, sometimes when you use .308 in a 7.62 rifle, the added headspace, higher pressure and thinner wall can make the brass expand and deform in the chamber, and sticking and jamming has been reported. With me so far? SOMETIMES the 7.62 has been chambered small enough that a typical .308 round will not float around at all.

        Now, why is this? It’s all about history. Think back to when this round (7.62) was developed. There’s a requirement for this round that isn’t talked about much but played a significant role in the wall thickness and the longer head space. The round had to be acceptable for full automatic machine guns. The higher pressure was unwelcome as it would affect recoil (think of the out-of-control climbing that ruins the effectiveness of small arms machine-guns). It also affected rate of fire and barrel heating up. So, the less pressure, the slower rate of climb, the less wear and tear, and the ease of using differently sourced rounds. The M-14 was the original recipient of this and later the M-60. I’m not certain but I believe there was an attempt to convert the M1919 over to this, but I could be wrong. If so, please don’t tell my son. Or my wife, for that matter.

        So, we still have military reasons for keeping the 7.62 round as-is in the form of modern full auto arms. Get the headspace checked against go-no-go for both rounds. Pay a gunsmith to do this as he or she (there you go, Hillary!) should have these tools. Though simple to use, fairly expensive for something you may use only once unless you’re a serious hand loader.

        The makers of the rifle you have a question on seem to be saying that the headspace on that rifle is a bit longer than usual for a .308. If so, you might maybe be trading a bit of accuracy just to have that flexibility of using either round. I don’t get the point here, as .308 comes in any sort of configuration and price break you could think of. Your “cheap” rounds of 7.62 might cost you down the road in terms of accuracy.

      3. Tim, from one vet to another, yes you can use both. The rounds are supposed to be interchangeable. You will want to be careful with the country the ammunition comes from, though. Some countries have poor to no quality control, thus their ammunition is not made to Nato specs. Stay with IMI or Western European ammunition, notably British, German, Austrian Polish and Belgian surplus. These countries have good quality control procedures in place. Don’t buy anything loaded before about 1980. Also, check it to ensure it will chamber properly in your rifle. If it won’t, break it down, dump the powder and primer, and re-size the brass if it is boxer primed. At least you will get a supply of brass. If it won’t chamber and it is berdan primed, you’ll just have to toss it. Most of the German brass is boxer primed. So is IMI (Israli Military Industries) and PPU or S$B brass. British 7.62 is almost always Berdan primed. What branch were you in? I was Army Infantry for 20 years.
        Elton P. Green SSG USA INF. Ret.

    10. Myself, I would be wary of using spent .308 brass for reloading purposes unless I knew exactly what rifle it had been fired through prior to ending up on the range floor. The stretch of .308 brass fired through unknown 7.62×51 chambers could result in empties that -might- head separate without warning due to the “headspace stretch” -ALL- occurring at the base end of the case and NOT at the shoulder/body length area (which would happen in carefully fireformed brass).
      All those reloading articles explaining when to discard rifle cases due to the displacement of brass from the base area of a casing (due to thinning) could provide pertinent information about this phenomena.
      I learned to pay this circumstance closer attention when I became interested in reloading for my Rolling Block rifle (and some of my Mausers) that are marked 7mm for use in Latin America during the late 19th and early 20th centuries.

    11. I’ve read lots of articles on this subject. And I like to ask the same question and see how many different answers I get from each article. OK here it goes-I have an M1A loaded with .308NM (National Match) stamped on the barrel. So what can I shoot? Some people say of course you can use both and some people say .308 is too hard on the auto loading mechanism, it’s strictly for bolt action. Some people say since it’s stamped .308 on the barrel it’s chambered for .308 and that ammo works better in that rifle. Now I’ve only run maybe 30-40 rounds of .308 through but I’m wondering if I should start buying the 7.62 NATO. I’ve spent more than a little money on this gun and I sure don’t want to cause me or the rifle any damage. All I want is the facts ma’am.

      1. The simple answer here is that the BARREL is marked .308NM. It means that the barrel has been made to a certain degree of accuracy. It does NOT mean that you can or should change calibers to the 7.62 NATO. It’s still a .308, man. You really want to jam 7.62 into what must be a fairly expensive barrel to start? Even if you get the round to cycle, please think of what you are doing to the chambering. M1A NM means that has been set up for .308 target shooting or sniper activity. If you have an M1A that has been chambered for the .308, you (or someone) had to change a few of the 30-06 gas piston components, not to mention the stock itself. So, your argument that the rifle can’t handle the round is senseless. And in a rifle that was originally set up to handle the 30-06? After how many rounds do you imagine this failure to take place?

      2. Ignore Mr. Romeu. If it says it will accept both, it will accept both. If you are really concerned, call Windham Weaponry and confirm. And thank you for your service.
        Elton Green, SSG, USA Inf., Ret.

      3. The NM barrel for the M1A has a match chamber, which is on the tight side of the chamber tolerance for the .308 Win. cartridge. It will fire 7.62X51 safely if it can chamber the ammunition. In other words, if the ammunition is within US Military Ordinance Department specifications. If you buy surplus ammunition, check it to insure it will chamber properly. If the bolt won’t lock up, the ammo is out of spec. Disassemble it and re-size the brass for reloading. If it will chamber properly, it will be safe to fire. Again, the two cartridges have EXACTLY the same external dimensions with the only difference being case thickness being greater in the military version and the pressure average being 4,000 psi lower in the military cartridge. Stay away from the Italian, Russian and Spanish stuff. Also, stay away from any South American surplus. Poor quality control with these countries means you don’t know what you’re getting. Israli, German, Polish, South Korean, Greek (mostly) and US surplus ammo is pretty reliable. I’m shooting Greek 30-06 in my CMP M1 Garand.

    12. I made the mistake of shooting 308 commercial brass which I reload in my m14
      I have a R.E.M. 7600 in 308 so I used same loads in both
      The m14 ripped apart the brass from long head space blew the mag out of rifle through the shooting bench, the stock split up to my cheek I thought my fingers were gone I couldn’t feel them and was afraid to look if my rifle hadn’t been a military rifle I’m sure I would have been killed all the pressure went down and not back into my face
      Stick with the right ammo for the Gun you are shooting

      1. I had the very same experience with a Mosin M1A when the round jambed in the chamber when and the bolt slammed home, blowing up the round, cracking the stock and peppering me with mini specs of blood all over my arms, but I didn’t find any cuts on me? Luckily, I sold the busted up rifle at a gun show for a grand!?! THAT was even more amazing???

      2. Who made your M14/M1a? I’m curious as to the manufacturer because it sounds like it may have been improperly head-spaced. This might not have been due to your loads.

    13. Have a m1 caliber .30 springfield armory on back of rifle , the barrel is made by h&r in 7.62 nato sa 11010457 dated 5 65 was told it came the navy, the question is ,is it safe to put factory 7.62 x 51 win. without blowing up, I tried putting shell in front of barrel it looked a little tight not coming to the rifle case , could use your comments, thank you.

      1. @Don B, No one is going to answer your question because it could become a legal issue. Perhaps you could take it to a bona fide gunsmith for a physical in person inspection.

      2. @Don B, Try using the ammo that is stamped onto the barrel and refrain from ANY experimentation whatsoever.

        ALL attorneys for accident, injury, liability lawsuits will tell you the exact very same, AFTER THE FACT OF YOUR, “EXPERIMENTATION” else they would make no money off of your unlicensed, unauthorized, unregulated stupidity.


      3. Mr. Bozeman, I will not do like Mr. Romeu has done and comment on your question like you are foolish in asking it. Instead I will give you the same advice that Wild Bill did. And maybe a little more. First, the rifle you have is probably worth around $2000.00, so I would not experiment. Take it to a gunsmith and have him use a go/no-go guage or a field guage on it to determine headspace. Second, have him check the magazine (clip) area and make sure there is a spacer present. One is required for the M1 when converted to 7.62×51, since it is a shorter round. Without this spacer block, the rifle won’t feed. Third, if the headspace passes the go no-go guages or the field guage, I would use only match grade Hornady ammunition in the 165 grain to 168 grain weights, which are specifically designed for 7.62×51 rifles, but only after the REPUTABLE gunsmith has passed on the rifle as safe to fire. Also, just so we can clear up a few things, if you check with the Civilian Marksmanship Program, they will probably be able to tell you if you have a military conversion, and if you ship it to them, they will not only check it completely, but certify it as safe to fire with commercial and Nato ammunition when they are through. That may be your best bet. You can find them with any search engine. Hope this answers what I think is both a reasonable and legitimate question. Elton P. Green, SSG, USA, Inf. Ret.

    14. I have a pair of Indian made Enfield rifles in 7.62 NATO. I have had one round that the head separated from the case while I was shooting them at the range . The gas vented back into my face but fortunately I was wearing my razor fly shooting glasses. I was using Steel cased wolf 308. When this happened. I had already fired several hundred rounds out of the rifles with nonproblems. I no longer shoot anything but 762 Nato surplus through my various 762 bolt actions. I at one point purchase several cases of the steel case wolf 308 and have used it in most of my rifles without problem , but I’ve learned my lesson and will no longer do so .I have an Israeli k98 and 762 of VZ 58 in 7.62 a couple of FR-S and a couple of FR sevens. All of them have been put on a brass 7.62 NATO Surplus Ammo diet since the incident with my wolf Steelcase. I shot the rest of the Thousand round case of wolf through my M1As and my lrb M14SA without any problems

    15. Great article and a reminder for myself, since I own a M!A. After reading this article I went to my documentation and it listed my rifle as head spaced to 1.631. I believe this may be due to it being a fully loaded model, just a guess. I only shoot mil spec ammo in it, I had some commercial FMJ ammo where one case failed to eject and I had to remove it with a cleaning rod. I have not tried any major brands of hunting ammo, It may prove more reliable.

    16. Tom McHale, thanks for a well-done, genuinely helpful piece.

      I recently acquired a Mossberg 800AM in .308 Winchester, Mossberg’s entry into the center-fire weapon field. The weapon, because it was part of an estate ownership and though built in 1970 – 1972, is in 98% condition in both metal and woodwork.

      I called Mossberg to ask about the proper care and feeding of this beautiful lady. Their weapon specialist, while agreeing that the .308 is loaded more powerfully than the 7.62mm, strongly recommended that I not use the latter round in the weapon. He remarked that while I might get away with the practice of interchanging rounds, the 800AM was built and tested specifically for the civilian round. Out of courtesy he couched his observations about head-space and casing thickness in understandable terms, and I got the message.

      I have stayed alive with all my parts through some very dicey situations mostly because my Dad reared me to understand that when an expert tells me something, paying attention to it is about the smartest thing I can possibly do. And .308 in all its iterations is easy to acquire, anyhow.

      Thanks to you all for a fine discussion run.


      Harris Langford

    17. I have an M-1 Garand that was rechambered to 7.72 NATO and given the National Match treatment. It is hard on commercial .308 brass.

    18. Ha Ha , Because I’m a bit of a Dummy RE-Math and an OLD Marine at 81 yrs old and keeping up with the young studs! I’ll have to go with Viper in MT, and shoot what the gun calls for. Hold em and squeeze em gents! if your in the -V- ring I’d say your probably using the correct ammo.

      Semper Fi
      Machete Eddie
      Capt USMC (ret)

      1. Thanks for your service, and HuuuuuRahhhhhhh!

        It says what ammo to use right on the firearm. That’s what I run through each of mine except in the case of a firearm which has been certified for more than one (.357/.38Spl, .308/7.62, .22S/.22L/.22LR). For 21+ years. I was provided the correct ammo for my issue firearms and I never had a problem of confusing calibers.

        DaveW, MSgt, USAF (Ret.)
        Defensor Fortis

    19. HK G3 were 7.62 NATO. One of the improvements PTR did was chamber in .308. I have the PTR 91 and it digests everything just fine. .308 is more accurate though.

    20. I have a Mossberg .308 and out of curiosity I called the company and ask them. The gentleman I spoke with
      said I could shoot them with no problem. He said the biggest difference was the headspace and the brass.
      The military 7.62 was a little heaver but had not effect on the weapon. He did say that personally he
      would not soot the .308 in a weapon designed for military usage and the 7.62 though he had done so
      and had not had any problems but preferred to used modern weapons with the correct caliber as being
      the safest alternative. I have rant over 100 rounds of both types thru my weapon so far and have inspected
      the weapon with a bore scope and noticed no change or problem in the chamber nor the bolt facing.

    21. If their was a dangerous difference in the calibers then we would hear not stop stories of shooters blowing off their faces with the wrong round whether its 308 or a 223 issue. I can even recall about hearing such a story but only ones involving shotguns or five-seven reloads.

    22. I have two Savage Model 99’s. All I have shot in them is 308 commercial rounds. I have been considering trying some 7.62 X 51 FMJ to see how they perform, but now I may just stay with commercial ammo. I believe both were made in the 1950’s and are gaining value and I do not want to damage them in any way. Additionally, I have a Ruger Scout that says 308, but does not say 7.62 X 51. I guess I’ll contact the Ruger company to see if they have recommendations.

      1. I had the Ruger Gunsite Scout in .308 and I did contact Ruger about shooting 7.62 NATO through it and the reply that I got was that you can absolutely shoot 7.62 through it.

      2. I had a Savage 99 in .308 and no way the bolt would close on 7.62. I also have a Savage Hog Hunter in .308 and it seems to have a bit more generous chambering as I have been able to easily close the bolt on SOME military rounds. But the real question should be “Why in the world would you want to try this??”. A Savage 99 is never going to be used for long distance shots and should never be considered as a plinker that you are going to take to the range and blast away on cheap surplus rounds. So where is the need for the 7.62? Are you telling me that your ammo suppler doesn’t have .308? You may have fallen in love with the price break on European 7.62 surplus, but please consider getting something that that round was intended for, like a full auto M60.

      3. fishunter.
        i own 4 savage model 99’s.
        one in 250 savage, two in 300 savage, and the last one in caliber 308 winchester.
        in that one i’d NEVER SHOOT 7.62×51 IN IT.
        my advice to all here is STICK to the caliber your firearm was designed to shoot.

    23. Some days I’m just not smart enough to shoot a gun. That will be the day I have a 7.62 or 308. Whew. Seems to me the only safe thing is to fire what the barrel stamp indicates.

      1. Ahhh! Trying to impose common sense and logic into the world of firearms? Are you sure that’s a safe thing to do on an online forum full of people that refuse to use common sense and logic?

    24. I use 7.62X51 brass for my handloads that I run in a gas gun that I built.
      I trim to length( .308) and load using the .308 data. I look for pressure as I develop loads .

    25. I have a Browning Hog Stalker semi auto marked 308 only. It appears in all aspects to be the same rifle as the FNAR with exception to the camo finish on my rifle. I see the FNAR is stamped 7.62X51. Can you explain the difference?

      1. Yes, in one rifle the manufacture is telling you to use, .308 ammo and the other manufacturer is telling you to use 7.62×51 ammo???

      2. In reviewing a lot of the responses to this particular article it is showing proof to the world that the Liberals are right that there should be a disarmament being that a lot of you do not deserve or need to have firearms in your possession just by the dumbasses questions I am seeing.

        I have a website SELLING “Common Sense”! Feel free to stop by and purchase all you want at any time!

      3. The reason that the rifles are similar is that Fabrique Nationale and Browning have been affiliated for about 90 years. They are the same rifle made by probably the same factory with different names because one is sold in the US and one is sold in Europe. In the case of the FN rifle, it is stamped with the metric designation for the .308 Winchester. When I was stationed in Europe (notably Germany) I talked with several German gunsmiths. The commercial version of the 7.62 Nato is labeled 7.62X51, and exactly corresponds to the .308 Winchester. Also, further evidence that the 7.62 Nato and the .308 Winchester have the same external dimensions is that the M24 and M40/a1/a2 sniping rifles are stamped 7.62 Nato and the snipers that fire them are issued mostly Federal Gold Medal Match ammunition for use in them. These rifles have a 7.62×51 that is reamed to match specifications and headspace tolerances, and won’t chamber some of the foreign ammunition that is not held to the tolerances required by the US military. However, they will chamber American, German, English and Belgian 7.62X51 just fine because this ammunition is held to close tolerances. In fact, if you read FM 23-10, Sniper Training, when the M118, M118 LR ammo or equivalent isnt available, regular ball is used, after testing lot numbers for accuracy. This was true for the M21 system (highly accurized M14 with match chamber and barrel) too. Also, both Lake City National Match 7.62 and Federal Gold Medal match Grade .308 have been used interchangeably along with Hornaday match ammunition in .308 at the Camp Perry National Matches for around 40 years. Properly manufactured 7.62X51 NATO ammunition can be used safely in rifles made for .308 Win., and .308 can be used in any rifle chambered for 7.62 X 51 NATO as long as the chamber passes a head-space test with either the go, no-go guages or a field guage. Just remember that some of the rifles and ammunition made in 2nd or 3rd tier countries have poor quality control and don’t necessarily meet NATO specification regarding cartridge or chamber dimensions or head-space tolerances. If I were going to buy surplus ammunition is this caliber, I would stick with that manufactured in Israel, Brittain, Germany or Belgium. They have good quality control. Keep in mind also that any US commercial rifle is proof tested. It is checked for pressures of around 75,000 psi to insure its safety. Good hunting.
        Elton P. Green, SSG, USA, INF. Ret.

    26. I don’t think the pressure in the Tsar Bomba was enough to “alter the trajectory of Michael Moore’s daily Krispy Kreme run.”

    27. Have a browning short trac marked 308 only. Have fired IMI 7.62 and functioned OK. Should I continue to use it or go 308 only.

      1. The IMI commercial 7.62X51 is .308 Winchester made by Israel using the metric designation. (Germany does the same thing with its commercial .308 because they also use the metric system, although when I was stationed in Germany, some of their .308 Winchester was stamped with both designations.) It is made to US tolerances, and I have fired it in both bolt guns and semi-autos extensively as practice ammunition. It is also very good brass for reloading. Don’t be afraid of it. I use it in my Remington 700, a Savage model 10, and an H&K 91. It functions beautifully and is quite accurate. Your Browning (good rifle, by the way) should be able to digest it pretty much without a hitch until you shoot the barrel out. It also works very well in M1A rifles as long as the rifle is in good condition.
        Elton Green SSG, USA, INF, (Ret.)

      2. The country of Israel uses the metric system. The IMI brand of ammunition is labeled accordingly. IMI 7.62X51 commercial ammunition is .308 Winchester ammunition labeled under the metric designation. Germany does the same thing with their .308 Winchester commercial ammunition too. But since they accommodate American shooters and hunters (mostly military stationed there) they will label most of their ammunition as .308 win/7.62X51. (I know that Germany does this because I was stationed in Germany for about 4 years.) The IMI brand of ammunition is completely safe in your rifle as long as your rifle is in good condition. It is made to SAAMI specs by one of the countries with the best quality control in the world. I’ve used IMI ammunition as practice ammo in Remington 700’s, a Savage model 10, several of my friend’s M1A’s and my HK 91 with no problems of any kind, and the brass is great for reloading. By the way, that’s a really nice rifle.
        Elton P. Green SSG, USA, INF. (Ret.)

    28. Have a Browning Short Trac says 308 only. Have fired IMI 7.62 and functioned fine. Should I continue or 308 only?

    29. I’ve shot both in my Marlin .308, never had a problem with length of 7.62. Nwow that’s not to say I won’t but I’ve fired 1000’s of rounds with not problems.

    30. I just read your your article about MOA vs MIL. My question is how does a 20 MOA rail figure in to tje calculation?

      1. A 20 MOA rail doesn’t affect calculations at all. It simply gives you more range adjustment. If you’re not zeroed at 100, and adjusting your elevation for longer shots, you don’t need a 20 MOA rail.

    31. Please note: the difference in headspace length is only 5 and 1/2 thousandths (or 55 ten thousandths) of an inch according to the numbers you show. The only way you can get 15 thousandths difference is between .308 min and 7.62 max.

      1. It’s no different than a barrel stamp 5.56 or .223. It means for the manufacturer’s warranty purposes they will accept and you will be in compliance within their limits of any liability to use either or round in that rifle.

        1. That is not correct. 5.56 military rounds can be much longer than .223 by design not just by stacking tolerances. If such a military load is chambered in a .223 the projectile will be lodged against the rifling creating a potentially catastrophic high pressure condition.

          When we use civilian .308 round in a military chamber we are fighting the larger chamber allowances in the 7.62 rifled. The thin civilian brass in conjunction with large military chamber allowances can create a situation where we see ruptured cases. Except for the poor quality control demonstrated in some military surplus ammo that was mentioned in the article, that is the only real concern.

          1. Well golly gee? Then I guess you better hurry up and run and tell the manufacturers of these chambered rifles that you know so much more better than them or their engineers???

            1. you guys are all nucking futts!…..just shoot what you’re supposed to shoot through the gun…….geeeeez….

        2. Now there is an answer that explains my whole Question Thank you very much. I am happy to find out that I am not a blind monkey on crack. Some people are not worth the effort to talk tp pr about

      2. Mr. Romeu is correct. If it is stamped both 7.62X51 and .308 Win. it is safe to shoot both. Just make sure the 7.62X51 NATO is within tolerances and you’ll be ok. If it chambers with little or no effort it is within tolerances. And yes, some 5.56X45 NATO is longer than .223 Remington ammunition, but that is overall length, not differences in casing. If the rifle is stamped to accept both .223 Rem and 5.56 NATO, it has a chamber with a long (military specs) leade in front of the casing, and is safe with the 62 grain bullet loaded in surplus ammunition. If you’re going to use heavier bullets, keep them at that overall cartridge length and you will be sufficiently within chamber length tolerances to be safe. By the way, I don’t think you can find milsurp ammo for 5.56 with bullets that weigh more than about 62 grains anyway. But again, I’d stay away from the Russian steel cased and some of the stuff from third world countries because of poor to no quality control unless you’re buying it just for the components.
        Elton P. Green SSG USA, INF. (Ret.)

      1. Probably just fine as long as it’s from a modern and reputable manufacturer. If it’s from Breszchzzk Ordnance arsenal made in 1958 then that might be a different story 🙂

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