Exploring the Effective Range of a .450 Bushmaster

While “Big Bore” mania has been circulating for a while now, a newer cartridge is finding its way to the head of the popularity pack: The .450 Bushmaster.

If you want a closer look at the history behind this powerful cartridge, its specifications, who it’s for and how to build a .450 Bushmaster rifle, then you’ll love this article.

Let’s get started!

History of the .450 Bushmaster

When Col. Jeff Cooper, a United States Marine who fought in WWII and the Korean War, was in the heat of battle, he needed rounds he could depend on for powerful, armor-piercing shots and deadly accuracy.

The rounds commonly used by military forces at the time just weren’t enough for him.

So, when he got back home, Cooper came up with the idea of a cartridge similar to the one found in his .45 ACP pistol that would work for a wider variety of firearms.

LeMag Firearms took his idea and ran with it, creating the .45 Professional cartridge that was later turned over to Hornady so that they could mass-produce the cartridges for Bushmaster’s AR-15 rifles.

It was dubbed the .450 Bushmaster.

The .450 Bushmaster wasn’t widely used until recently, and now, the round is being produced by major manufacturers including Federal, Buffalo Bore and Remington.

Why the sudden interest?

A relatively new change in gun laws makes it so that hunters in the Midwest can now use straight-walled cartridges in their semi-auto weapons.

A posse of medium-game hunters that were itching to use their AR’s flocked to ammo shops and many ended up choosing the .450 Bushmaster because of its reasonable price.

Now, the .450 BM is one of the most popular straight-walled cartridges on the market.


Savage 110 450 Bushmaster
Savage offers an accurate and affordable package for firing the .450 Bushmaster.

.450 Bushmaster Specifications

The .450 Bushmaster’s dimensions come in just under maximum legal limits, maximizing power and distance.


Here are the specifications:

  • Rim diameter: .453 inches
  • Overall length: 2.25 inches
  • Shell-case length: 1.7 inches
  • Bullet sizes: Between 245 and 300 grains.
  • Muzzle velocity: 2,200 ft/s, 200-yard velocity at 1,500 ft/s.
  • Muzzle energy: 2,700 ft/lb, 200-yard energy at 1,200 ft/lb.

This cartridge packs a serious punch, but what about its range?

450 Bushmaster Winchester Ammo
Winchesters .450 Bushmaster ammunition is a great choice for deer hunting.

Bushmaster .450 Effective Range

With as much energy as this cartridge generates, you’re going to get a larger range.

I found this was definitely true for the .450 Bushmaster that was giving me between 1.5 and 2.5-inch groupings at 100 yards.

That was a lot more accurate than my .45-70’s were getting.

Pace that out to 200 yards, and I was still getting some great accuracy. 300 yards is about the max range for this cartridge as it will start seriously dropping.

The optimal conditions for longer-range shots would be shooting from a stand during mild, windless weather.

Also, to maximize range, you’ll want a high-quality scope like the EOTech XPS Holographic. Speaking of scopes, let’s talk building.

Building a .450 Bushmaster Rifle

If you’ve already got a standard-built AR-15, then you’ve got half of a .450 Bushmaster rifle in your hands.

With a few tweaks to the upper assembly, I created a killer weapon that wasn’t too hard on the wallet.

The first thing I did was pick up a .450 Bushmaster upper assembly. Rock River Arms makes a great assembly that I’ve been very pleased with, but any assembly that fits a 5.56/.223 receiver will work.

The next (and MOST IMPORTANT) thing I did was change out the mags.

If you don’t do this, you can get some massive misfeeds and a lot of headaches. Lancer mags seem to work well — especially if you throw on some Tromix followers.

Boom. Now you’ve got a completely operable .450 Bushmaster rifle with minimal effort.

You WILL want to fit your rifle with some sort of muzzle device if you want to keep your shoulder in working order.

I like the Precision Armament Hypertap because it effectively mitigates the powerful blast generated by .450 BM.

If you don’t already own an AR and still want to get in the .450 game, I highly recommend the Ruger American Rifle Ranch that is already set up and ready to go for .450 Bushmaster cartridges.

450 Bushmaster AR-15
Any standard AR-15 can be converted to fire the .450 Bushmaster, but you can always buy one that is already optimized.

Why Use the .450 Bushmaster?

There are several reasons I got into shooting .450 Bushmaster.

But the main reason ended up being the fact that I could use this cartridge in places that I couldn’t use traditional bottlenecks.

It’s great for clean, quick and humane kills on medium-sized game like deer, elk, hogs and some bears.

It deftly out-performed the .350 Legend at the 250 to 300-yard range.

It also maintains much greater downrange energy than other rounds like the .223 Remington, which makes the .450 Bushmaster a great choice for competitive shooting as well as hunting.

The .450 BM is also very reasonably priced.

450 Bushmaster Buffalo Bore Ammo


Overall, this newly-popular round is exceptional at getting your shot further downrange with maximum power.

Here are some of the highlights:

  • Accurate
  • Legal for more areas
  • 250 to 300-yard effective range
  • Easy to build from an already-owned AR-15

So, if you’re looking to blast a hog, take down a deer across the field, or place in the top scorers at competition, you don’t want to overlook the .450 Bushmaster.

Have you tried the .450 Bushmaster cartridge? What did you think of it? Let us know in the comments below!

About the Author:

Richard Douglas

Richard Douglas is a firearms expert and educator. His work has appeared on large publications like The National Interest, Daily Caller, American Shooting Journal, and more. In his free time, he reviews optics on his Scopes Field blog.
The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (40)

  1. *Update*My Bear Creek Arsenal (BCA) AR15 with a flat faced Timney trigger is the most accurate gun I’ve ever owned, and I’ve owned MANY makes of bolt guns in many calibers!!
    Sub MOA at 100 and inside a 3 inch circle at 300 yards using my Leupold 450 Bushmaster 3-9 power scope. This scope is outstanding, just range and dial up to 300 yards calibrated for the Hornady 250 grain ftx. Bought a Wilson combat lancer magazine and added the Tromix follower and cut out a half circle using a dremel at the top front of magazine. This magazine has been 100 % reliable after over 150 rounds!

  2. My Bear Creek Arsenal (BCA) AR15 awith a flat faced Timney trigger is the most accurate gun I’ve ever owned, and I’ve owned MANY makes of bolt guns in many calibers!!
    Sub MOA at 100 and inside a 3 inch circle at 300 yards using my Leupold 450 Bushmaster 3-9 power scope. This scope is outstanding, just range and dial up to 300 yards calibrated for the Hornady 250 grain ftx.

  3. I have two 450bm rifles one is a bushmaster carbine, the other is a Ruger American ranch. So far I have taken four nice whitetail bucks and a cow elk all animals were taken inside of 100 yards. The elk was drt the bucks ranged from drt to making it less than 25 yards. All were shot with the Hornady ftx factory ammo. Both these rifles are 1″ to 1 1/2″ performers at 100 yards. The bushmaster also shoots the 300 grain bear load very well the Ruger not so much. I haven’t taken any game with them yet. Overall I love this cartridge and the rifles are great. The Ruger is topped with a SIG Romeo 7 the bushmaster has a vortex strike fire 2

  4. i shooting 450 bushmaster with winchester 250 g bullet,,how high at 100yds to be on at 200yds?1830 fps at 100 and 1510 fps at 200?

  5. Yea the 450BM is a nice round for Deer in Michigan. I own two of them, a Gunsite Scout and CVA stainless. I would not suggest a 0 power EOTech XPS2-0 Holographic, you need a decent 3-9x.
    I shot two one at 195 yards and other at 140 yards.

    If you go with a bolt action gun you can really step up the performance, but even with toned down AR you can get Barnes 450 TTSX BT 250gr factory.

    If you want to go past 200 yards I would suggest a high BC copper Bear Creek Ballistics round. They do make one for the AR platform too. The round is very accurate, out of my Gunsite Scout I had a sub 1″ group at 200 yards. At 100 yards I’m usually 1″ and under with both guns.

    Shoots at 2450fps out of my scout and 2550 out of the CVA (25″ barrel). With its high BC + velocity it adds 100 yards to the range and still has 1400FPE at 400 yards. (Hornady is around 650FPE)

    If you want pass-through for blood trails the FTX tends to break apart on bone = 1 hole and less blood trail. I had one with ZERO blood no exit.

    For most hunters probably 200 yards and under, the wind can really move them. Was blowing my rounds 6″ left at 200 with 12 mph wind.

  6. I own 5 450bm (Ruger American, 20″ AR, 16″ AR, 8″ AR pistol, and a Encore 20″) and love them. I hand load so I experiment on a regular basis. Using the Ruger American and the Encore, I can load to 460 S&W specs.. The cases hold the same amount powder. A 250 ftx @ 2500 fps is a heavy hitter. Even with factory loads, you can hunt any critter in North America. Fact is that most helpful hunters don’t shoot past 300 yds. The average range for deer kills is 125 yds. In the shtf, it is perfect for reloading using 45 acp bullets. The average distance war time kills of soldiers is less than deer. It also uses the same bullet as a 20 gauge slug (Hornady, Remington sabots). You can easily paper patch lead slugs. You can resize 45-70 lead. It is a perfect round.

  7. Article never mentions .223 used by Col Cooper in Korea. How did people read that into the article? Relevant text says:


    The text of the article stands as it was written.

  8. I bought a Ruger American Rifle in Go Wild Camo. It is Cerakoted (not very evenly) with 22″ barrel and a multi ported muzzle brake. The magazine holds 3 rounds and clicks into place tightly. Comes out easily though having gloves on makes it a little difficult. I’ve had no problems with feeding or extraction. I mounted a Leupold VX R 3x9x40 in Warne QD 30mm rings. Sighting in was fairly straight forward. The gun has a lot of recoil and rise. I sighted in 2″ high @100yds. It shot 2″ low at 200yds.
    I was shooting Hornady Black 250gr and Remington Premier 260gr. Both shot well but the Hornady grouped a little better. I also shot into 5, 1 gal milk jugs filled with water at 100yds. Bullet passed through all 5 jugs and buried in the hill behind. Also shot 1/4″ mild plate steel. At 100yds bullet made perfect 45 cal hole in steel plate.
    In November I used it on a whitetail hunt in Saskatchewan. I shot a nice 10pt the 1st afternoon. He was facing almost head on at 103yds. When he turned slightly and opened the right shoulder I shot. He jumped hard to the left and disappeared into the brush. Guide came out and we tracked the buck 50yds. Certainly did the job. Broke the upper right front leg. Entry hole was the size of a grapefruit, no exit wound.

  9. When Col. Jeff Cooper, a United States Marine who fought in WWII and the Korean War, was in the heat of battle, he needed rounds he could depend on for powerful, armor-piercing shots and deadly accuracy.

    The 5.56 NATO rounds commonly used by military forces at the time just weren’t enough for him.

    I hate to tell you this, but 5.56 rounds were not used in WWII or Korea. They did not see use until Vietnam.

  10. How does this weapon compare to my Marlin 444? My gun has been around for 25+ years, and had given me similar results. The bullets even look similar. My gun’s range is excellent for a saddle gun, and there are few large game that have walked away once I got a bead on them.

  11. I built and upper out of quality parts. Faxon 18” barrel, Aero precision XL upper receiver, Faxon bolt carrier group, buffer spring and buffer recommended for 450 BM. Bought 5 different magazines, because of all of the trouble people have posted about feed problems. ( I have not tried your recommended magazine combo).
    This thing I s a cannon, love the power, but it fails to feed constantly, and in all different scenarios. It may be that it needs to wear in more. Not sure..
    Accuracy, in real world, off the shoulder, I’m good for 75 yards, maybe still needs to break in the barrel. Maybe I’m a terrible shot. But compared to my 308’s, the 450BM is not accurate. I need more time with this gun. I will try your mag suggestion.

  12. I would like to see a comparison with the .460 Magnum. I’m always looking for my next large bore revolver.

  13. I haven’t checked out your blog before. Very informative. I will be a regular from now on

  14. I have been on the fence about my next rifle purchase. I’ve eyed the 450 BM for a little whilr but keep coming back to the .308. I live in Florida so there aren’t a lot of opportunities for many 1000yd shots. I primarily hog hunt hogs so this article is helping me to
    finally decide, although in the back of my mind I’m thinking the 308 would serve me better in a SHTF scenario. Hell maybe ill just buy both.

  15. Recently built a Bushmaster on. Savage Axis action using a Rhineland 16” barrel with 1/16” twist. Rifle loves the 250 grain FTX and 300 grain XTP-MAG Pushed by Lil Gun powder. Velocities are 2236 and 2995 FPS respectively. 1” at 100 yds for the FTX and 1.4” at 150 yds For XTP.

  16. What would be the cost of turning my Bushmaster .223 into a .450 Bushmaster and what parts will be needed? Will the parts have to be sent to a FFL or can they be shipped directly to me?

  17. Sir, great article. Would the .450 BM with a 300 grain bullet be effective in hunting Bison, thanks

  18. Sir, great article. Would the .450 BM with a .450 grain bullet be effective in hunting Bison, thanks

  19. This was a very interesting and well-written article on an ammo I knew nothing about. Thank you. However, I presume the author had an only momentary lapse when he said the 5.56 was commonly used in WW2 and the Korean war. I’m sure he meant the .30-06.

  20. This is an interesting article, but I shy away from calibers that are costly to shoot. I dont have any need or desire for the .450BM. I’m ok with the 5.45mm NATO. Added a 300 BLK recently and may get out of 7.62mmx39 altogether since there are more bullet loadings in 300 BLK that make it more versitile than 7.62×39.

  21. I doubt that Colonel Cooper had much contact with 5.56 rounds during World War II or Korea. They just weren’t that common. Perhaps you meant to say some other NATO round. Otherwise very interesting article. Thanks for sharing.

  22. The article is incorrect in regards to the 5.56 NATO M16 being used in WWII and the Korean War. The 223/5.56 NATO was accepted by the U.S. Military in 1963 well after both wars. I’m going to guess you meant the M1 Carbine 30 caliber which was basically under powered for what it was used for. The .450 BM definitely is and improvement over the 30 caliber in power and Muzzle energy.

  23. I just got a new .450 Bushmaster and really love it so far. I’m a reloader and already reload for .45 Colt and .45 ACP and have a lot of .451-.454 bullets. The fact that it’s a straight wall cartridge is why I chose this over the .458 Socom. Also the fact that you don’t have to deal with neck creep etc makes it nice. Make sure you plan to get single stack style magazines though as the offset double-stack AR type mags just don’t feed this round well. I’m loading it with Hornady XTP Magnum 300 & 243 grain hollow points, which have worked terrific on game with my .45 colt carbines at these velocities. The FTX is ok for target/defensive shooting, but I find that it opens too quick on deer size varmints and damages a bit of meat.

  24. The 5.56 x 45 NATO wasn’t in use during World War II and Korea. It’s introduction into the US Military didn’t happen until 1964 (and it wasn’t formally adopted by the NATO countries until 1980, even though it had been in service for 16 years), long after Col. Cooper’s Military Service ended in 1955.
    Col. Cooper was dissatisfied with the .233/5.56 x 45, and helped with the development of what eventually became the .450 Bushmaster, but it was for its use on Large Game out to 250 yards, not its use as a battle rifle. The calibers used during Col. Cooper’s service would have been the 30-06, .30 M1 Carbine, and .308/7.62 x 51 NATO. His experiences with the M-16/AR-15 would have been entirely post military.
    Just noting a historical inaccuracy in the article.

    1. Thanks for the polite correction (not all comments have been as cordial). We’re in the process of verifying the information and updating the article.


  25. The 450BM is an excellent “brush gun” caliber as well. I sent half its 250 grain bullet through a 2×6 fence board’s edge at 15yds and onward to a 50yd target, and yet the bullet strayed less than 6″ from the bullseye.

  26. From the experience I’ve had with my .450 BM, everything in the article adds up, plus I learned a couple things. I agree that you should really look into getting mags specifically for it. They say you can use standard AR-15 mags, but I had a ton of feeding issues, and most of the time, I just ended up feeding them manually one by one. It does pack a serious punch to your shoulder, even with the Buttstock that I bought for it. I’m good for 20-30 rounds at the range with it before I just don’t want to put anymore impact on my bruised shoulder. I’ll have to try out a new scope for it too, seeing as the optic I had for my 5.56 wasn’t really cutting it. Couldn’t get very good grouping. Good to know the effective range is 250-300 yards. I’d love to get it dialed for hunting.

  27. First I wanted to say thank you for all the information. In your article When you mentioned having to switch out the standard .556 magazine, and you recommended LANCER. Is it a proprietary magazine to the 450 or does one .556 magazine feed the .450 better than the other? If so can you send me a link to the magazine that you recommended we try to have the best experience possible. Thanks again.

  28. I have it in the Ruger American ranch rifle… it pushes the Barnes 290 grn tipped boattail muzzleloader bullet at 2150 fps and will shoot cloverleaves at 100 yds. Weighs a hair over 6 1/2 lb with a Hawke slug IR scope … it is currently my favorite deer gun, and the best brush gun I have ever used.

  29. The .450 BM is exceptionally accurate out of an AR-15 platform using the Hornady 250gr. FTX load. Sub-MOA is not at all unusual.

  30. I just purchased a ruger 450 American rifle with a 22in barrel over the typical 16. I took it to range with several boxes of Hornady Black 250 grain. I ranged at 60 yards using a Strikefire II red dot. It took a good hour to get it dialed in and producing tight patterns. I am not a professional just a hunter trying out this combination because I have been looking for a new deer rifle. I’m not sure how it will perform when its 30, in a tree but its lighter and pretty manageable for the longer barrel. Oh it has a kick and it’s very loud even with the muzzle break.

  31. I built a 450bm last year I love the round shoots great but I’m still having feed issues. Can’t rely on maltable shots. Not that you need them with the 450 bm.. One hell of a wallop!!!!

  32. I have had and shot a 450 BM for two years and it is more accurate than this article states. I have shot a deer in the ear at 193 yards off a bench the gun can do it I cant without help from a bench. At 65 yards a perfect between the eyes. Both shots were witnessed no bull. I shoot the Ruger American and love it. PS my scope cost more than the gun.

  33. Good article except 5.56 NATO rounds were not commonly used by military forces during WWII and the Korean War.

  34. Do you think Ruger would consider making a .450 Bushmaster in semi auto just like the .44 magnum they’ve made for years? What a nice little NE deer rifle that would make with the increased energy over the .44.

  35. The 5.56 NATO round wasn’t adopted by the US military until 1963. The Korean conflict ended in 1953. So, that round wasn’t used at the time. The small arms ammunition in use for rifles in WWII And Korea includes 30-06, .30 carbine, and .45 ACP (Thompson machine gun).

  36. Hey good article. I’ve been wanting to get more info on this rifle round. I’ve been thinking about building one for hunting myself.


  37. Hello, I’m not sure if you realize that the 5.56/M16 was not put in service until Vietnam. The way the second and third paragraph is written makes it sound like Col Cooper used the 5.56/M16 in WWII and Korea and we know that is not accurate. Anyways, thanks for the article

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