Experimental IMR Enduron Powder Loads – Discussion & Results

Editors Note : Caution, Reloading is dangerous, read our “Reloading Disclaimer“. The IMR Enduron Powder load data published by this website is intended discussion purposes only. As with all data collection, mistakes are possible. You have been warned.**

U.S.A. –-(Ammoland.com)- It seems every day new items including guns, ammo, bullets, new calibers, scopes and various other shooter related items are released.

Another new item is gun powders that have characteristics not present in the older propellants. Over the last few years, there have been some novel improvements. Bright spots include gun powders that have chemicals in them that are used to reduce copper fouling.

In addition, the new powders are not heat sensitive a problem that has been around for years.

Hodgdon – The Gun Powder People ( www.hodgdon.com ) has the rights to the IMR line of gun powders so I have been dealing with Chris Hodgdon in regards to these powders in various rifles. The Hodgdon folks have done a lot of development with the modern and common rifles so with Chris’ feedback, I have done some work on them as well

I am focusing on new IMR powder loads for rifles that are obsolete but can deal with a modern type of smokeless powder loads.

Military surplus rifles are common and I have worked a lot on them, from the early smokeless powder loads through the WWll rifles. There are many of these guns still around and with the reasonable prices that they have, popularity is still good. These guns are well made, durable and unless they have been shot excessively or are abused, they are still well worth shooting. For those who like to hunt, they are powerful and accurate enough to get the job done. For the most part, brass and bullets are plentiful or at the worst can be made by the experienced handloader.

In this test, there were a few obsolete sporting rounds. With these powders, I am looking for good performance, which includes good accuracy and velocity with safety in mind. Trying to exceed the original ballistics is not my goal but some improvements did happen on some occasions. If this was achieved without excess pressure then that would be acceptable.

When working up loads with any powder, caution should always be exercised. Start on the low side and carefully work your way up until you get the safe load that you are seeking.

Since every rifle is an individual these loads should be used as guides. As you develop your own loads you will get different results with your rifles. All of these loads listed were tried out by me and not copied from another source.

I did not do much with modern magnum rifles because that data is available and with limited time and resources, I didn’t see the point. I did try a couple of loads in the 7 mm and 300 Win mags and the results are promising. If I ever go on another hunting trip and use a suitable rifle for one of these powders I will work up the loads and use them. At some point, I will work with the 8 mm Remington mag as the 7977 should really do well especially with a heavy bullet.

Recently IMR introduced four new powders. They have a feature known as Eduron technology. A couple of features of this technology is a reduction in copper fouling and it is insensitive to temperature changes.

It seems that every day a new powder is coming out. Most reloaders have favorite powder for their guns but with the supply problems having backup loading info on powder alternatives is always a good idea. Since data has been worked up for the common guns, I don’t see any point in duplicating someone else’s work.

Many of the WW l and WW ll guns are still around and the owners want to shoot them. Brass and bullets are still available, so as long as the gun is safe why not shoot it.

IMR Gun Powders used in this study Include:

• 7977 IMR Enduron Powder
• 4166 IMR Enduron Powder
• 4451 IMR Enduron Powder
• 4955 IMR Enduron Powder

Having worked with the new IMR Enduron powder I have observed some of the following characteristics. They are an extruded item resembling many of the other IMR powders. They don’t appear to be heat-sensitive per a couple of tests I did. In my powder measure tool, they are NOT very consistent. I may get several good throws then one will increase anywhere from ½ to a grain. With that observation, I measured each charge on the ones for serious work. Maybe it will meter better in another powder measure tool so the best advice it to try and observe it in yours.

I have listed virtually all of the loads including the ones that were too warm. The purpose is to inform the reader and to use caution when approaching the max loads, as they are listed as a study only. These are new powders and as with all handloading, each gun is an individual and what is ok in my weapon may be too warm in yours or the reverse can be true. In quite a few instances, the new powder gave some more velocity. More importantly, they gave good accuracy and consistency, meaning a low standard deviation from shot to shot. In some cases, you can take your rifle and improve on these loads if you take the time to research and observe your own results.

As for the brass used it was whatever I had available with no effort to sort it by brand or weight.

Contrary to some opinions brass with mixed headstamps can produce very consistent and accurate ammo. As long as the brass is in good shape, it will work.

You will note that some bullets were loaded backward. One reason is the flat point bullet wasn’t available therefore a boat tail bullet backward was used. That makes it safe in a tubular magazine rifle. Most of the time they were as accurate as the same bullet loaded in a normal manner. In addition, you might get more penetration as the back of the bullet is stronger and the info gathered makes it interesting to test a bullet this way. I have done this with various rifles and is seldom disappointed with the accuracy. As with all testing pay attention to pressure signs.

The 223 is the most common round being made, so we start with the assumption that IMR 4166 Powder should work well.

First tests indicate that 4166 doesn’t work well in the 223 as it is slow and produces a high es and the loads were compressed. Further testing produced better results.

The 100 grain was fired in a rifle with a 1 in 7” twist and a 16” barrel. We tested to see if they will stabilize in that twist. The 100-grain bullet stabilized at 100 yards showing some good accuracy potential. Looking at the tables it will become noticeable that with some loads adding 1 grain of powder causes a major increase in velocity. That is something to keep in mind when working up loads.

223 IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
27 grains 4166	50 gr. Privi	3237.83	Good Load
27 grains 4166	53 gr. HP	3193	Good Load
26 grains 4166	50 gr. Privi	2926	High ES Slow
25 grains 4166	55 gr. FMJ	2721-16"	High ES Slow
26 grains 4166	55 gr. FMJ	3221.59---20"	Good Load
21.5 grains 4166	90 gr. Sierra BT HP	2364	WARM!
21 grains 4166	100 gr. HP	2269 16"	Nice

The 22-250 Bullet is a top performer in the 22 centerfire class. It is my favorite 22. This cartridge has been around for many years as a wildcat before Remington adopted it in 1965. It is a very flexible round and I have put many pasture poodles to rest with it over the years. For that purpose, a 50 or 55 grain seems to be the best option.

22-250 IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
36 grains 4166	50 gr. Privi	3934.1	High ES
35.5 grains 4166	53 gr. HP	3700.87	Fair
35 grains 4166	55 gr. FMJ	3658.7	Very High ES
35 grains 4451	77 gr. HP	3196.59	Decent Load
32.5 grains 4451	100 gr. HP	2792.2	High ES

The 243 Bullet should respond well to some of the new IMR powders.

The 243 Bullet is versatile and with the proper bullets is adequate for deer and similar size game. I have used it for groundhog hunting and it is slightly superior to a 22 if the wind is blowing. Most of the time I used an 85-grain Sierra, as it was the most accurate bullet in that particular rifle.

As always, keep in mind that different guns like different bullets and powders.

243 IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
39 grains 4166	65 gr. Hornady	3312	Consistent
38 grains 4166	75 gr. Speer HP	3158	Mild
36 grains 4166	80 gr. Sierra BT SP	3174.8	Consistent
37 grains 4166	80 gr. Privi BT SP	3212.6	Nice Load
41 grains 4451	100 gr. Sierra BT	2981.14	OK

The 25-35 Bullet has been around for many years. Most are lever action, hence they need a round or flat nose bullet to prevent chain fires. Unfortunately most bullets won’t work & no one makes suitable bullets so I will be loading the bullets backward to produce a flat point.

In the past boat tail bullets have been used by me with success. Since the original bullet is 117 grains, a boat tail bullet should work fine.

**Bullet loaded backward. Boat tail bullets are used for loading backward because with their profile they feed better.

25-35 IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
25 grains 4166	90gr. Sierra BT *	2266	Mild Not Consistent
24 grains 4166	100 gr. Privi	2258.7	OK
22 grains 4166	117 gr. Hornady *	2118	Consistent

The 257 Roberts Bullet has been around for many years and I have a converted Mauser to test a few loads. The rifle is a converted Mexican Mauser which was originally a 7 X 57.

I can get more velocity out of a 257 but I didn’t fully trust that rifle with high performing loads and it also was not my gun. Therefore, I throttled back. Perhaps at a later date, I will be able to pick up another rifle and try again.

257 Roberts IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
38 grains 4166	87 gr. Hornady	2786.8	Fair-Slow
43 grains 4451	87 gr. Hornady	2623.38	Slow
45 grains 4451	100 gr. Privi	2597.5	OK
45 grains 4451	100 gr. Privi	2645.67	Second Test
43 grains 4451	117 gr. Horn	2534	Good Load
45 grains 4955	117 gr. Hornady	2662.67	Nice

The 25-06 Bullet started out life as a wildcat but later on Remington adopted it. For long range on some deer and antelope it would be hard to beat. Later on I will do some more testing with this round.

25-06 IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
52 grains 4955	117 gr. Sierra	3169.2	OK=Accurate

The IMR 4451 has a burning rate close to 4350 which will make it versatile. Since many of the common rounds are covered I will go over some of the military such as the 30-40 Krag and similar rounds.

The 6.5 Jap came out to replace the 8 X 53 Murata.

The case is small but due to the strength of the action, loads can be made to compare to some of the other 6.5 caliber rifles. Like most of the 6.5 caliber military guns ammo used a 156-160 gr FMJ RN which gives some good penetration but lacks the stopping power of a larger round.

Lighter, soft point bullets are better for hunting as they possess more velocity and open up upon impact. The action is considered one of the very strongest in existence. It is almost impossible to blow one up as tests have shown that the barrel has been blown off but the action held. That doesn’t mean that you should try and make it a magnum round. There are other limits to consider.

How does it handle gas if there is a rupture? A well designed action such as the Mauser model 98 vents the gas away from the shooter’s face.

Also the case will give up before the action does. Barrel length is a very important factor with velocity. I have chronographed many long guns and handguns and almost without exception a longer barrel produces more velocity. When you take notes of your readings keep that in mind. That is especially true with large cases and max loads.

6.5 Jap IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
34 grains 4166	139 gr. Privi	2468.18	Nice
36 grains 4451	160 gr. Hornady	2284.28	Consistent

The 6.5 Daudeteau was the military round used by Uruguay in the 1890’s.

It is a conversion of the model 71 Mauser converted to fire this round. France also used the round to a small amount during the same period.

There is no commercial brass or ammo available so it has to be made. The 7.62 X 54 Russian cases seem to be the best option. With a good selection of bullets and some common sense it can be a decent hunting round. While well-made it has only one locking lug so that should be remembered. The Daudeteau loads are right where they should be.

I used the slowest powder as the rifle has only one locking lug so trying to increase velocity a lot would be foolhardy. The long barrel does help increase the velocity.

6.5 Daudeteau IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
47 grains 7977	140 gr. Hornady	2574	OK
46 grains 7977	160 gr. Hornady RN	2400.44	Nice

The 6.5 Dutch is the forerunner of the 6.5 X 54 Mannlicher. It is offered in the model 95 but is not available commercially in the United States although possibly could be found in Europe. The rifle is well made with a smooth action and with good loads it is a good hunting round for deer size game. The carbine is light and handy to carry with an 18” barrel. Cases have to be made from 303 British brass which is available. With a good selection of 6.5 bullets, it is a desirable round if you don’t mind a little extra work.

The 120-grain load was excessive and the load would have to be reduced by at least 3 grains or use the 4451 powder as it is slower. The Dutch has a short barrel so obtaining much more velocity would be difficult and unproductive. As a note, the extractor broke during the test but we just poked them out until I fix it.

6.5 Dutch IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
37 grains 4166	120 gr. Sierra	2631.12	Nice Consistent
40 grains 4166	120 gr. Sierra	xxx	Too Hot!
40 grains 4451	140 gr. Hornady	2472.75	Consistent
39 grains 4451	160 gr. Hornady	2308.5	Nice Load

The 6.5 Carcano was one of the earlier smokeless rounds introduced by the military powers. Italy brought it out to replace the 10.4 Vetterli and it served through WW ll.

The Carcano rifle is not highly regarded by collectors and shooters as it is considered inferior to most other period rifles.

However, for those in the know, it is a much better weapon than it is given credit for.

There is a good selection of bullets and, with a little common sense, it will give a very good performance. The Carcano loads can be increased somewhat, although common sense should apply. With this gun, I did start mild and worked up to the top loads listed. It has a short barrel which will put a limit on the velocity. The last 160-grain load is consistent and due to the very short barrel it will be difficult to get more velocity without excess pressure. A 24” barrel would increase velocities by 150 to 200 FPS. If I get a longer barrel Carcano then I may work with these loads some more.

6.5 Carcano IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
40 grains 4451	120 gr. Sierra	2479	Consistent
38 grains 4451	139 gr. Privi	2321.5	Mild
36 grains 4451	140 gr. Hornady	2168.1	Very Mild
37 grains 4451	140 gr. Hornady	2241.2	OK
35 grains 4451	160 gr. Hornady RN	1972.1	Very Mild
36 grains 4451	160 gr. Hornady RN	2012.33	OK
37 grains 4451	160 gr. Hornady RN	2148.09	Very Consistent

The 6.5 X 55 Mauser round along with the model 96 are highly regarded by shooters and collectors.

Due to the fairly large case capacity, I felt that the 4451 would work well with heavy bullets. The 4955 has a burning rate similar to H-4831 powder so it should work well in this round with heavy bullets. A couple of the velocities are higher than expected. There are no obvious signs of excess pressure but I would strongly recommend starting 2-3 grains below on the loads listed as warm. After some further examination and work, I found that they are a bit too hot for general use. There is no excessive swelling or difficulty in sizing which are signs of pressure. The cases were new Privi so measuring the head after firing might not be totally accurate. A few of the primers seated too easily which is a definite sign of excess pressure. The Mauser model 96 is a great, well-made gun and is the best Mauser action other than the 98.

As noted velocities were higher than normal which should raise a flag.

There are some legitimate reasons for that such as a long barrel or fast gun but any sign should be reviewed. This gun is 100 years old so that should be taken into consideration. Extra velocity may be desirable but not in all cases. The standard deviations (SD) on the warm loads are pretty low, easily within standards for such guns. In general, a high SD means that the load is too light though not always. Safety and caution should come before anything else especially when working with new and unknown powders. This applies to all guns especially the older ones that are tested in this piece.

6.5 x 55 Mauser IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
44 grains 4451	120 gr. Sierra	2878.98	OK
41 grains 4451	139 gr. Privi	2449	High ES
43 grains 4451	139 gr. Privi	2756.2	Better Load
45 grains 4451	139 gr. Privi	2839.17	Consistent
47 grains 4955	139 gr. Privi	2935.92	Awesome=WARM!
41 grains 4451	140 gr. Trophy	2494	More Consistent
44 grains 4451	160 gr. Hornady	2647.27	Nice
46 grains 4955	160 gr. Hornady	2754.5	Nice WARM!

The 270 Bullet has been around for a long time and is used by many hunters. The rifle used is a Remington 721. This is another round that has benefited from improved bullets and powders. These Enduron powders show a great deal of promise in this round. There is a good selection of bullet styles and weights.

270 IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
60 grains 4451	90 gr. Sierra HP	3656.25	WARM!
60 grains 7977	130 gr. Speer	2876	Slow
56 grains 7977	130 gr. Speer	2876	Slow
59 grains 7977	140 gr. Nosler	2880	Consistent
58 grains 7977	150 gr. Hornady	2761	Nice Load
60 grains 7977	150 gr. Hornady	2965.33	Very Consistent

The 7 mm-08 is a versatile round well worth having. I purposely left some of the loads sitting in the sun until they got so hot it was hard to load them. I wanted to see if there were any spikes in the loads and none were evident so the claim that it isn’t heat sensitive has some merit. I did that with some of the 30-06 loads also. Like any other rifle, loads should be approached from below and carefully worked up. Each rifle is unique and so are the loads.

7mm-08 IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
45 grains 4166	100 gr. Sierra HP	3156	Good Load
41 grains 4166	120 gr. Hornady Flex	2943.27	OK
45 grains 4451	140 gr. Sierra BT	2746.83	OK
46 grains 4451	154 gr. Hornady	2666	Nice
44 grains 4451	162 gr. Hornady	2580.22	Good Load
44 grains 4451	162 gr. Hornady (backwards)	2596.17	Decent
45 grains 4451	162 gr. Hornady	2683.11	WARM!
43 grains 4451	175 gr. Hornady	2546.78	Nice Load

The 7 X 57 Mauser has been around for many years and is one great round with a strong gun and modern loads. There are some older rifles out there that should avoid max loads. The model 93 that has the rolling block, although a good gun, should not be used with max loads.

The gun used in this test is a model 98 that was re-barreled so heavy loads can be used. With top loads, it is capable of a lot of large game hunting and with the great selection of bullets that is enhanced. These loads should not be exceeded and in a weaker gun such as a 93 should be cut down by at least 2-3 grains.

The 175-grain load was way too hot and blew one primer and the rest shows definite signs of excess pressure. As odd as it might seem the load was outstanding in regards to consistency. ES of 43 and an SD of 16 which is really consistent.

Going through my records I have found that loads that may be too warm to use have a good es and sd though not always. The barrel on the test gun is 26” long which definitely adds to the velocity and should be factored in when determining how good the load is.

7 x 57 Mauser IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
47 grains 4166	120 gr. Sierra	3073	MAX - Consistent
45 grains 4166	139 gr. Hornady	2931	Nice Load
48 grains 4451	154 gr. Hornady	2761	WARM!
47 grains 4955	160 gr. Sierra	2712.75	MAX - Nice
46 grains 4955	175 gr. Hornady	3578.3	MAX - Very Consistent
49 grains 4955	175 gr. Hornady	2671	Too Hot!

The 7 mm Remington mag was tried with two of these powders.

The 7 mm Remington mag which came out in 1962 is the most popular belted case. There are a couple of reasons for that. Especially with the new and improved bullets, it can handle almost any hunting situation. Recoil isn’t excessive while accuracy is very good with most loads. Components are readily available which is another plus with this round.

At a later date, as time permits, I plan on some more work with this round as I feel that more performance can be realized. In addition, there is published data on this round.

7mm Remington Mag IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
68.5 grains 4451	100 gr. Sierra HP	3396	Fair
65 grains 4451	120 gr. Hornady	3322.22	OK
71 grains 7977	140 gr. Privi	3094.89	Consistent
71 grains 7977	145 gr. Speer	3018.92	OK
71 grains 7977	154 gr. Hornady	2971	Mild
67 grains 7977	174 gr. Privi	2818.78	OK
67 grains 7977	175 gr. Hornady	2794.62	Consistent
68 grains 7977	175 gr. Hornady	2899.7	Decent

7.35 Carcano was brought out in 1939 by Italy. Due to the start of WW-II, the Italians went back to the 6.5 and sold most of the 7.35 rifles to Norway. It takes an odd diameter bullet usually .298 and the 4166 seems to work well in it.

7.35 Carcano IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
38 grains 4166	122 gr. Milt	2431	High ES
39 grains 4166	122 gr. Milt	2453	More Consistent
36 grains 4166	150 gr. Speer RN	2214	High ES
37 grains 4166	150 gr. Speer RN	2223	Better than 36

The 30-30 has been around forever and no test would be complete without it. So we used four different bullet weights with 4166. The 4166 is definitely a viable powder in this chambering. The 4166 is the fastest burning powder and along with the relatively small case they make a perfect match.

Note the difference that a single grain can increase results. That is why when working with a new powder it is prudent to be cautious.

30-30 IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
35 grains 4166	125 gr. Sierra	2532.78	Consistent
33 grains 4166	150 gr. Hornady RN	2344.83	OK
32 grains 4166	160 gr. Flex Tip	2284.36	Decent Load
31 grains 4166	170 gr. Speer	2151.83	Fair
32 grains 4166	170 gr. Speer	2238.79	Nice Load
31 grains 4166	180 gr. Hornady RN	2045	Consistent
32 grains 4166	180 gr. Hornady RN	2251.18	Nice Load

The 30-40 Krag was introduced in 1893 and continues to be used for hunting and target shooting. Since it has limited strength caution is advised when working with the top loads. A long barrel 28” was used for these tests.

30-40 Krag IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
46 grains 4451	180 gr. Sierra RN	2401	Very Consistent
46 grains 4451	180 gr. Sierra BT BKS*	2356	Consistent
46 grains 4451	180 gr. Sierra BT	2344	High ES
48 grains 4955	180 gr. Sierra RN	2532.67	Very Consistent
44 grains 4451	200 gr. Speer	2159	OK
42 grains 4451	220 gr. Sierra RN	2126	Mild High ES
45 grains 4955	220 gr. Sierra RN	2286	Nice

**The 180 grain Sierra BT soft point loaded backward was much more consistent then loaded normally. I have found that in a couple of other instances. I don’t have an explanation for that.

The 7.5 X 54 French Mas round was used during WWII as it replaced the 8 X 50 Lebel.

The bolt action rifle is well made though the locking lugs are located in the rear of the bolt, an uncommon feature. There is some military ammo available but it seldom goes off. All of it I have acquired ended up having the bullets pulled. Brass is available from Privi and it takes standard 30 caliber bullets. If you can’t find the brass then 6.5 X 55 Swedish can be necked up and shortened.

Power wise it is the equal of the 308 which makes it a very useful hunting round. These loads equal most 30-06 loads which would indicate excess pressure. However, there are no obvious signs of stress but I strongly recommend starting at least 2-3 grains below and carefully working up. Upon closer inspection and work it was found that the cases were harder than normal to size which can be an indication that the loads are too hot. That along with the excess velocity should give us pause. The primers were a little loose but not enough to throw away. Measuring cases show some expansion but since they were new cases it is an indication but along with the other signs caution should be the procedures used.

7.5 X 54 French Mas IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
46 grains 4166	150 gr. FMJ	2788.92	Nice
49 grains 4166	150 gr. FMJ	2947	Consistent - WARM!
45 grains 4166	165 gr. Privi	2714	Consistent
46 grains 4166	180 gr. Hornady	2763.91	Nice - WARM!
46 grains 4451	180 gr. Hornady	2397.08	Mild

The 7.5 X 55 Swiss is a good candidate for this powder and bullets.

Case capacity is very close to the Russian so the same loads will be used. These are high-quality rifles though they are a straight pull design. The earlier version came out known as the model 89. It has a slightly shorter case and loads are much lighter as the locking system isn’t as strong as the newer models. These loads are for the new models and shouldn’t be tried in the model 89. With the top loads work up carefully from below. The loads listed as hot are for information only and should not be used. That applies to all calibers.

7.5 x 55 Swiss IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
45 grains 4166	150 gr. FMJ	2830	Nice
47 grains 4166	150 gr. FMJ	2944	Very Consistent
43 grains 4166	165 gr. Privi BT	2614.37	OK
46 grains 4166	165 gr. Privi BT	2838.5	Nice
50 grains 4451	180 gr. Sierra	2687.7	Consistent
53 grains 4451	180 gr. Rem	2668	WARM!
52 grains 4955	180 gr. Rem	2678.36	Consistent
52 grains 4451	200 gr. Speer	2668	Hot!
48 grains 4451	200 gr. Speer	2543.1	Nice
50 grains 4451	220 gr. Sierra	2365	Too Hot!

I would recommend that all of these loads be dropped at least 2 grains. All show signs of pressure and excess velocity. It was hot during testing which would be a factor but still dropping 2 grains would be a good idea. I hit the jackpot with the 150 and 165-grain loads using 4166. I have been finding that it is a top powder for these cases in regards to velocity and consistency. The 4451 is a great powder for the heavier bullets showing good results. Again do not use the loads that are listed as warm or hot. It isn’t necessary or safe and the loads are listed for information only. As much as I like 4895 the 4166 is as good or better in a lot of loads. No pressure signs were observed in the good load listings.

The 308 has been around since 1950 and we have two different semi rifles to test.

Both rifles were consistent with that load though they were near max. I have a Ruger model 77 which should enable us to get the most out of the 308.

*Bolt action rifle loads*

308 IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
46 grains 4166	150 gr. Sierra *	2934	Consistent
41 grains 4166	150 gr. Privi	2519 Garand	OK
41 grains 4166	150 gr. Privi	2508 LAR 8	Consistent
41 grains 4166	150 gr. Privi	2479 FAL	Consistent
42.5 grains 4166	150 gr. Privi FMJ	2752.4	Rock River LAR-8
42.5 grains 4166	150 gr. Privi FMJ	2717.89	M1-A Springfield
44 grains 4166	165 gr. Hornady *	2776.1	Consistent
43 grains 4166	180 gr. Sierra	2562.78	Nice
42 grains 4166	180 gr. Remington *	2671.1	High ES
41 grains 4166	200 gr. Speer	2372.3	Consistent

The 30-06 is the most versatile round in existence so there will be a lot of info as all four of the powders will work for something though may not be the ideal powder such as the 7977.

The slowest is 7977 which will be suitable for various large magnums. I am trying one load in the 30-06 but I suspect that it will be too slow to produce max velocities with a 220 grain. It would indicate that this powder is a bit slow in the 30-06 even with a heavy bullet. If you can drop tube in a couple of grains more that might help but it would be a time-consuming effort.

The Garand load is close to what I want. For the Garand, I used military brass. The ES was somewhat high in the Garand rifles but a little tweaking of the charge will resolve that. They fed and cycled perfectly with no signs of excess pressure. With the 165, 180, and 200-grain loads I used commercial brass but, it was once fired of various brands and I didn’t sort it out, just made sure it wasn’t too long. The loads are very promising as the velocities are really good and they are consistent. I didn’t see any signs of excess pressure and they extracted perfectly. I will test them in other rifles to verify the results. I am running a second test with the 165, 180, and 200-grain bullets in a different rifle but with the same brass to check for pressure signs. Two stars (**) indicates the second test.

The second rifle was a 03 Springfield with a 24” barrel. The results are similar to the first test and some loads showed signs of pressure and these loads should be approached with extreme caution. Start from 2 to 3 grains below and carefully work up. I did not have any problems with sticky extraction with any of the loads but in other rifles that may very well occur. I did not look at any data before I started this project with the thought that it would help me get a good idea on how these powders perform. Afterward, I checked some tables and my results were close to the book loads. In some instances, these powders will produce a little extra velocity.

**Caution Reloading is dangerous, read our “Reloading Disclaimer“. The load data published by this website is intended discussion purposes only. You have been warned.**

30-06 IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
48 grains 4166	150 gr. FMJ	2613.3	Tanker Garand 18"
48 grains 4166	150 gr. FMJ	2623.67	Garand 24"
48 grains 4166	150 gr. FMJ	2727.09	Nice
49 grains 4166	150 gr. FMJ	2854.3	Consistent
50 grains 4166	150 gr. Sierra	3014.92	Very WARM!
51 grains 4166	150 gr. Sierra	3055.75	Hot!
57 grains 4451	165 gr. Hornady	2901.7	Nice Load
57 grains 4451	165 gr. Hornady**	2895.08	Consistent M-12
56 grains 4451	180 gr. Hornady	2779.75	Consistent
56 grains 4451	180 gr. Sierra	2807.83	Very Consistent
56 grains 4451	180 gr. Hornady**	2860.56	Hot!
56 grains 4451	180 gr. Sierra**	2857.7	Very WARM!
64.5 grains 7977	180 gr. Remington	2726.5	Not what I expected
55 grains 4451	200 gr. Speer	2657.1	Good Load
55 grains 4451	200 gr. Speer **	2737.89	Nice - Max
61 grains 7977	220 gr. Sierra	2379	High ES
54 grains 4955	220 gr. Sierra	2527	Nice - Max
57 grains 4955	220 gr. Sierra	2639.42	Still Too Hot!
61 grains 4955	220 gr. Sierra	2786	Way Too Hot!

***The 4955 will probably be more suitable for the 220 and heavier bullets, rather than the 7977.The 61-grain load is much too hot and under no circumstances should be used. The primers were blown out and there are prominent ejector marks on the cases. The 54-grain load with the 220 is absolutely the max that should be used. It shows very slight pressure loads in the Blaser used so I would drop down a grain or so in another rifle. Over 2500 is definitely on the high side for a 220-grain bullet. With the 4955 and the 220-grain bullet, I would strongly recommend starting at 51 to 52 grains. As always each rifle will react differently to the same load.

The 300 Win mag has been around for over 50 years and continues to be popular and a couple of these powders should work well in it. Due to some published information, I did not spend a lot of time with this round though I have no doubt the the proper

Due to some published information, I did not spend a lot of time with this round though I have no doubt the the proper Enduron powders will perform very well.

300 Win mag IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
81 grains 7977	165 gr.	3084.09	Consistent
76 grains 7977	180 gr.	2882.18	Mild

The 4166 is the fastest of the four new powders so will start there for loads of 7.62 x 39. I didn’t see it listed for this powder but I thought it may work with this load. I was surprised in the velocities as they were higher than I expected. Loads functioned action perfectly. I was skeptical of the results as they produced more velocity then I expected so I did them again and even used a different chronograph.

* Second test. So it appears that this powder would be a viable alternative with the heavier bullets.

7.62 x 39 IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
27 grains 4166	150 gr. Privi	1949	Workable
27 grains 4166	150 gr. Privi	1936*	Consistent
26 grains 4166	174 gr. Hornady RN	1896	OK
26 grains 4166	174 gr. Hornady RN	1776*	OK

The 30 Harrett is a cartridge for a single shot handgun. Since it has a capacity very similar to the 7.62 X 39, the thought was to try similar loads in it. Since it has a shorter barrel the velocities will be lower. Cases are formed from 30-30 brass, as there is no factory fodder available. The results were surprising and especially the 165 which has a SD of 8.96 which is exceptional. The velocities are very similar to the 7.62 X 39 considering the 39 has a longer barrel. Either would make a decent deer gun at closer ranges.

30 Harrett IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
28 grains 4166	150 gr. FMJ	1881.38	Nice
27 grains 4166	165 gr. Privi	1850	Very Consistent
27 grains 4166	170 gr. Speer	1793.22	Fair
26 grains 4166	180 gr. Hornady RN	1745.62	Real Consistent

The 7.7 Jap served during WW-II and is still fairly common today. With that thought tried some 4451 in it. It takes the same diameter bullet as the 303 British and 7.65 Mauser rounds. With good loads and bullets, it is close to the 30-06 in power and has a good enough bullet selection to make it versatile. If you want a heavier than normal bullet Hawke makes them in 190 and 220 grain RN types. These powders seem to bring out the best in the Jap round. Without much doubt, I can get a little more velocity but I don’t see the point in stressing an old rifle just to get a few feet per second more. These loads are adequate for most hunting situations. Note the difference in the 49 and 50-grain loads. They were done on different days but temps were similar so I would consider 50 grains to be a max load although there were no pressure signs.

7.7 Jap IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
50 grains 4166	123 gr. Hornady	3239.78	Nice
50 grains 4451	150 gr. Sierra	2711	Good Load
50 grains 4451	150 gr. Hornady	2727.62	Consistent
48 grains 4451	174 gr. Hornady	2376	Mild High ES
49 grains 4451	174 gr. Hornady RN	2365	Mild
50 grains 4451	174 gr. Hornady RN	2648.89	Real Consistent

The 7.62 X 54 Russian has been around since 1891 replacing the Berdan round. It has the advantage of a plentiful supply of rifles at very reasonable prices. Many countries used them and they are still used in some of the backward countries. Ammo and brass are relatively easy to obtain so you are in luck. It has approximately the same power as a top end 308 and is capable of good accuracy. It might not be a bad idea to slug the barrel as I have seen some go from .308 to .316 so in order to get the best accuracy use the correct diameter bullet. Factory ammo usually has a .310 diameter slug. I would not recommend increasing the top loads.

7.62 X 54 Russian IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
51 grains 4451	180 gr. Speer RN	2372	Consistent - Mild
53 grains 4451	180 gr. Speer RN	2455	Nice Load
52 grains 4451	200 gr. Speer	2416	Good Load
50 grains 4451	220 gr. Sierra	2317	Very Consistent

The 303 British is one of the most widely known military rounds so the 4166 should be a good powder in it. The 303 came out in 1888 with a compressed load of black powder and a 215-gr FMJ RN bullet. In a few years, however, they went to Cordite and a lighter spitzer bullet. Today the 303 is still widely used by collectors and in some backwoods countries, it still can be used.

303 British IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
45 grains 4166	123 gr. Lapua FMJ	2856.44	Consistent
45 grains 4166	123 gr. Soft Point	2836.67	Consistent
43 grains 4166	150 gr. Sierra	2702.3	Decent Load
40 grains 4166	174 gr. Hornady FMJ	2449.3	Nice
40 grains 4166	180 gr. Speer	2450.08	Consistent

The 7.65 Mauser is another fine round and one of the earlier smokeless powder rounds. It came out in 1889 and was used by various countries and the 91 Mauser was an early rifle that used it. Later the model 1909 came out with it. The 1909 is a model 98 Mauser and was considered one of the best Mausers ever made. It uses the same projectiles as the 303 British and the 7.7 Jap. The top loads with the 150 and 174 are very consistent but should not be exceeded. There was a big difference between the Hornady 174 grain RN and the FMJ. While that is a larger than normal spread between bullets of the same weight it reminds us to finalize a load with the exact bullet that will be used such as a serious hunting load. You can also observe the difference that a grain or two of powder can make. That is why there are cautionary notes all through this piece.

7.65 Mauser IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
50 grains 4166	123 gr. Flex Tip	3079	Consistent
46 grains 4166	150 gr. Hornady	2478.09	Mild
48 grains 4166	150 gr. Hornady	2891	Nice - Max
44 grains 4166	174 gr. FMJ Hornady	2225.9	Mild
44 grains 4166	174 gr. Hornady RN	2641.5	Nice
46 grains 4166	174 gr. FMJ Hornady	2717	Consistent - Max

Sometime between 1890 and 1900, Germany brought out the 8.15 X 46. It is a German version of the American 32-40 both in power and use. It was popular for 200-yard matches because of it good accuracy and low recoil. Bullet diameter is usually .318 though slugging the bore might not be a bad idea. I have made ammo for several of them including one that I owned. Cases are made from a 30-30 or 32-40 brass that needs to be trimmed and sized. Some of the older guns were originally designed for black powder and caution should always be used. Some 98 Mausers were rebarreled to this round and can safely utilize modern type loads. Due to the small case power being limited it would barely be adequate for deer with the best loads at close range. It is however, an enjoyable round to shoot due to its light recoil and good accuracy. For the Mauser, I had to dress down the rim in order to make them fit. It was only a small amount but, using a drill and file was time-consuming.

German 8.15 x 46 IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
32 grains 4166	125 gr. Hornady	2397.2	Decent
30 grains 4166	150 gr. Hornady	2296.27	Fair
28 grains 4166	170 gr. Hornady .318	2029	Nice Load

The 8 X 50 Lebel can benefit from mild loads especially the model 86 used in this test. It has a tubular magazine which prohibits using pointed bullets so I have loaded one backward. With bullets loaded backward you can’t use compressed loads as the bullets go in crooked so that is a limitation we have to live with. That applies to all of the rifles I have tried. A little shopping can produce bullets from 125 to 220 grains so almost everything is covered.

8 x 50 Lebel IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
52 grains 4166	150 gr. Hornady	2951.4	Consistent
51 grains 4166	170 gr. Hornady RN	2159	Very Mild
48 grains 4166	175 gr. Privi backwards	2687.55	Very Consistent
45 grains 4166	174 gr. Privi backwards	2140	Mild
45 grains of 4166	198 gr. Privi FMJ	2491.09	Fair

The 8 X 52 Siamese Mauser came out in the 1920’s to replace the older 8 X 50. A modified Mauser 98 was used for this round. Since it is a large rimmed round the action had to be modified to accommodate this chambering. There is no ammo or brass available so 45-70 cases or 8 X 56 cases which I used. They have to be modified to be usable. There are a couple of commercial ammo makers who will make the brass or sell loaded ammo. Once you have the brass and dies loading is typical and it uses a standard 8 mm bullet. Since it is a 98 action good loads can be developed giving it adequate power for hunting.

8 X 52 Siamese Mauser IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
45 grains 4166	150 gr. Hornady	2654	Mild - Consistent
47 grains 4166	150 gr. Hornady	2731.5	Nice Load
45 grains 4166	175 gr. Privi	2540.4	Very Consistent
45 grains 4451	198 gr. Privi FMJ	2193.33	Mild

The 8 X 56 straight pull came out to replace the older 8 X 50 both use the model 95 straight pull rifle.

For some reason, they use a .330 diameter bullet instead of the regular .323 bullets. That makes it more difficult to get bullets though they are available. Privi does make the brass, so with a set of dyes you are in business. The round has enough power for most hunting and the rifle is well made. Personally, I don’t care for straight pulls but they function well and gives the owner an opportunity to build up their arms. Like some of the other military guns tested the velocities seem higher than normal. That may indicate excess pressure but none were present during testing. I would strongly advise starting 2-3 grains below and carefully working up. The barrel is short 18” so velocity would drop some as a result.

8 x 56 Straight Pull IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
52 grains 4166	150 gr.	2717.18	Consistent
50 grains 4166	175 gr.	2563	Nice Load
48 grains 4166	205 gr.	2395.27	Nice - WARM!

The 8 X 57 Mauser is one of the most common military rounds which came out in 1888 in the Commission rifle. The model 88 isn’t a Mauser action and is inferior to the 98 action. It also uses a .318 diameter bullet so if this data is used start at least 10% below the listed loads. I have a Commission rifle and at a later date will develop some loads for it. In 1904, the Mauser went to the .323 diameter bullet which is used today. Components are plentiful and easy to get. In a model 98 loads can be developed that will get the most out of this round. With top loads, it is close to a 30-06 in power. These loads should not be used in a Commission rifle. These loads should be reduced from 10 to 15% at least for use in a Commission or other weaker rifle.

8 X 57 Mauser IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
52 grains 4166	125 gr. Hornady	3245.45	Nice
50 grains 4166	150 gr. Hornady	2955.75	Real Consistent
47 grains 4166	175 gr. Privi	2713.81	Nice
46 grains 4166	185 gr. Remington	2575.7	Good Load
44 grains 4166	198 gr. FMJ	2454.75	Consistent
45 grains 4451	220 gr. Sierra	2304.91	Consistent

The 32 special came out as a companion to the 30-30. The idea was it was supposed to be usable with black powder, which was still common when the 32 was introduced. Unlike the 30-30, it never became very popular though it will do well in hunting deer in the woods. There are not very many bullets suitable for it though the 170 does just fine.

32 Special IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
35 grains 4166	170 gr. Speer	2201	Nice Load

The 358 Winchester has been around since 1955. In spite of the fact that it is a terrific hunting round it has never been really popular. During various time frames, a couple of companies made rifles. For this test, a Browning lever rifle is being used. It was bought in 1977 and has harvested many deer through the years. Like the 35 Whalen, it is flexible with the ability to use 38 caliber handgun bullets at reduced velocities. Later on, when I get a bolt action rifle in this caliber will resume testing as this is a much better round than sales figures indicate.

358 Winchester IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
50 grains 4166	180 gr. Speer	2536.51	Nice
48 grains 4166	200 gr. Hornady SP	2132	Surprise Slow

The 35 Whalen has been around and should do well with a couple of these powders. With good loads, the Whalen would be adequate for almost any large game. If you don’t like belted cases but want some serious punch this might just be the round that you are looking for. For light loads, 357 bullets are just the ticket. It is an extremely flexible round especially for the handloader.

35 Whalen IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
58 grains 4166	180 gr. Speer	3000.36	Nice
60 grains 4451	200 gr. Hornady	2610.8	Mild
58 grains 4451	250 gr. Hornady	2436	Mild

The 38-55 is an old round originally loaded with black powder. Happily, they have made some modern strength guns that can take advantage of the round. I have an H & R single shot, which allows the use of bullets not suitable for a lever gun and modern loads. The IMR 4166 may be on the slow side but will be interesting with heavier bullets. In modern type guns, 4166 is a viable powder.

38-55 IMR Enduron Powder Loads

LOAD / POWDER #	BULLET	VELOCITY	COMMENT
38 grains 4166	200 gr. Sierra	2073	Nice
38 grains 4166	200 gr. Sierra (2nd test)	2113	Consistent
37 grains 4166	220 gr. Hornady	2094.11	Consistent
36 grains 4166	235 gr. Speer	1947	Nice Load
35 grains 4166	245 gr. Cast	1925	OK
34 grains 4166	250 gr. Hornady	1963.7	WARM!

**Caution Reloading is dangerous, read our “Reloading Disclaimer“. The load data published by this website is intended discussion purposes only. You have been warned.**

About Bob Shell:

A Custom Reloader of Obsolete and Antique Ammo, Bob Shell, writes about the subject of Guns, Ammo, Shooting and Related Subjects. Visit: www.bobshellsblog.blogspot.com.