.450 Bushmaster Ammunition and Accuracy Testing

.450 Bushmaster Ammunition and Accuracy Testing
.450 Bushmaster Ammunition and Accuracy Testing

GRAND RAPIDS, MI USA -(Ammoland.com)- In my prior articles on the .450 Bushmaster, I built a hunting rifle with the help of Brownell’s and subsequently experienced major feeding issues with it. I solved these problems with the help of Tromix and got the gun running smoothly. In this article we will be looking at .450 Bushmaster ammunition and how to get the best accuracy out of your .450 rifle.

To start, we need to lay down some ground rules about the performance of the .450 in general. The round isn’t an especially accurate one by most standards, but it is very far from being a rock in a sock. The .450 is not a long range cartridge, but it is plenty good for hunting in virtually all places in the country except, perhaps, the wide-open plains. Most, including myself, believe it to have an effective range of about 250 yards. It generates a tremendous amount of power at close ranges and is, essentially, a very large pistol cartridge. You could think of the .450 as a large .45 ACP in almost every respect.

For this ammo accuracy and velocity test I used a very nice SWFA SS 3-15x42mm scope. This is an almost recoil-proof, tank of a scope that I’ve used for years. To mount it to the rifle, I selected the rock-solid Midwest Industries MI-QD30-SM quick-detach scope mount. This mount is able to stand up the recoil of the .450 with ease and returns to zero. This combination of scope and mount is what the .450 needs. You can’t have anything moving, especially what you aim with.

Building a .450 Bushmaster AR-15 Hunting Rifle with Brownells
Building a .450 Bushmaster AR-15 Hunting Rifle with Brownells

The ammunition that I’ll be looking at in this article comes from two companies: Hornady and Buffalo Bore. The ammo from Hornady comes in the form of two basically identical loads, one being the 250gr FTX Custom and the 250gr FTX BLACK. These loads are identical as far as specs on the Hornady site and have an advertised muzzle velocity of 2200fps. The bullets used for this load have Hornady Flex Tip technology and are widely known to be very effective.

The ammunition that I’ll be looking at in this article comes from two companies: Hornady and Buffalo Bore.
The ammunition that I’ll be looking at in this article comes from two companies: Hornady and Buffalo Bore.

The Hornady loads are some of the first to come out on the market for the .450 and they have always been solid performers. I have taken this load hunting in the past in a bolt action I built several years ago when the Michigan hunting laws changed to allow straight-walled cases.

L to R: Hornady 250gr FTX, BB 300gr JHP, BB 275gr XPB, BB 250gr JHP

I tested theses loads for velocity over my Oehler 35P chronograph and they came in exactly the same at average of 2165fps, which is very close to the stated velocity from the manufacturer (Hornady lists the 2200fps from a 20” barrel, mine is 16”) and was very consistent. The accuracy (after I figured out some issues) came in at 1.5” for five shots at 100 yards.

The Buffalo Bore loads are very new on the scene as of this year I received three different loads to test: the 300gr JHP, 250gr JHP, and 275gr XPB Barnes Lead Free. These loads are all a far cry from the original .450 offerings and two of them have conventional rounded pistol bullets in them as opposed to a pointy rifle bullet.

The claimed velocity for the 300gr JHP load is 1950fps. My rifle fired this load at a five-shot average of 1920fps. This load generated the most recoil out of any .450 load I fired and it also showed the most drop of any load, falling about 14” at 200 yards from a 100 yard zero. It was quite accurate considering the bullets used and generated 5-shot groups of 2.9” at 100 yards.

The next load, the 275gr XBP, has a stated velocity of 2000fps. My rifle fired it at 1922fps and averaged 2” for five shots at 100 yards. This was a very low-recoil load and it was very comfortable to shoot. I noticed that it appeared to also be slightly lower pressure judging by a rounded primer flatness and smooth, easy ejection of cases.

The next load, the 275gr XBP, has a stated velocity of 2000fps.
The next load, the 275gr XBP, has a stated velocity of 2000fps.

The final Buffalo Bore load is the 250gr JHP. The manufacturer says this is a load designed for deer hunting and has a bullet designed to expand at pistol velocities. At a claimed velocity of 2250fps and matching speed of 2249fps from my rifle, this load certainly was faster than pistol velocities, and produced the fastest speeds of any round I tested among this group. It was acceptably accurate at 2.5” for five shots at 100 yards.

The final Buffalo Bore load is the 250gr JHP. The manufacturer says this is a load designed for deer hunting and has a bullet designed to expand at pistol velocities.
The final Buffalo Bore load is the 250gr JHP. The manufacturer says this is a load designed for deer hunting and has a bullet designed to expand at pistol velocities.

So this brings us to accuracy and the mechanical accuracy of the rifle itself. My gun performed very differently with each of these loads and I had accuracy issues with the gun itself, not the ammo. I discovered that another problem that resulted from the magazines and the restriction of the action. I am not an expert on this by any means, but I noticed that the magazines had a real effect on how the gun shot.

When I loaded the gun with a single round and fired for group, it produced excellent accuracy. When I put a loaded mag in, I had groups open up and sprayed all over, often raising group size to double what the single rounds were. I discovered that when I used the Lancer magazines with the Tromix followers, the accuracy tightened. My thought on this is that the upward pressure being placed on the bolt carrier caused minute flex and put pressure on the upper receiver, pushing it away from the lower. This stress then caused the bolt carrier to operate sluggishly or move irregularly.

Does this mean that you have to be careful of what mags you use in your .450 rifle? At least in an AR you might have to. The AR is a design that wasn’t made to handle these big-bore rounds and is somewhat fragile to begin with, thus making a complex situation of trying to maintain accuracy while various pressures are exerted on your moving parts. The best thing that can be done for accuracy in a .450 is to not try to stuff so many rounds into a mag that the bolt can’t travel.

A topic that I brought up in my last article was case taper. The .450 is a straight walled case in that it has no bottleneck. It does have a minute taper from base to mouth and as a result the rounds can lift in the magazine.
A topic that I brought up in my last article was case taper. The .450 is a straight walled case in that it has no bottleneck. It does have a minute taper from base to mouth and as a result the rounds can lift in the magazine.

A topic that I brought up in my last article was case taper. The .450 is a straight walled case in that it has no bottleneck. It does have a minute taper from base to mouth and as a result the rounds can lift in the magazine. I noticed that there were some small differences in the shape of the Buffalo Bore loads as opposed to the Hornady offerings. The Buffalo Bore cases, most notably that of the 300gr JHP, have what could only be described as an undetectable difference in case taper that made it easier for them to lift up in the magazine with a standard follower installed. This problem vanished with the Tromix followers.

As far as the general accuracy of the cartridge is concerned, groups in the 1-3” range aren’t bad. I know there are some people that claim that this is terrible, but in real life it is fine. I shoot from field positions with the bipod and this is perfectly acceptable for hunting use.

There are many people out there that would have you believe that this is a one-hole cartridge at 300 yards, and I’m certain that there are many very accurate guns out there that can do it (the Ruger No.1 I will be reviewing in my next article is certainly one of them), but not every .450 is going to do that. The AR rifle has lots of complicated intricacies and making it accurate with a giant pistol cartridge is no easy feat. The bullets are not very aerodynamic, are very heavy, and relatively slow.

I think that each of these .450 cartridges has a place. Buffalo Bore, in addition to the three loads I tested, makes a 360gr hardcast lead load that was designed for bear hunting. I didn’t test it here, but the fact it exists shows the range of use the .450 has.

In the future there will likely be more good .450 loads available. I will be testing handloads in an upcoming article, and what you can expect to see when rolling your own, using some very fascinating bullets. The fact that the .450 is rapidly gaining popularity only serves to make me believe that I’ll see some fantastic bullets and amazing ammo types in the future. There isn’t much you can’t do with the loads I tested here, but it will certainly be nice to see the future of this cartridge.

Ammo for this article can be seen at www.buffalobore.com and www.hornady.com.

The parts for the rifle can be found at www.brownells.com, www.tromix.com, and www.midwestindustriesinc.com.


About Josh WaynerJosh Wayner

Josh Wayner has been writing in the gun industry for five years. He is an active competition shooter with 14 medals from Camp Perry. In addition to firearms-related work, Josh enjoys working with animals and researching conservation projects in his home state of Michigan.

  • 8 thoughts on “.450 Bushmaster Ammunition and Accuracy Testing

    1. I use rhe 450 Bushmaster for hogs , Hornaday black ammo , shots range from 50 to 100 yds . Seems they dont go far from where they were introduced to that bullet. I find this a fun gun ta plug pigs with.

    2. Have a very difficult time believing mats qfrect accuracy. Having fired tens of thousands of rounds in competition with the AR out to 600 yards mags don’t matter. Much more likely you are changing something other than single loading. Try using a timer between shots mag and no mag.

    3. I also use the Ruger American Ranch for deer and hog hunting in the Piney Woods of East Texas. I am also curious about your opinion of which would be best cartridge.

    4. Try the Hornaday black and Underwood loadings . The Hornaday and was he Underwood hunter loadings give. 1-1&1/2 at 100 yds in my Bushmaster upper! Perhaps I stead of blaming the bullet, the barrell could be the problem!

    5. Drt co makes 170 grain non lead bullets designed specifically for hunting with maximum kill effects cant wait to try them out in a ruger no 1 450 this deer season

    6. I will use the Ruger American Ranch with 16 inch bbl. for deer hunting. Curious to know your opinion of which of these cartridges might be the best fit with this rifle for that purpose.

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