New Cartridge: 45 RAPTOR

Imagine a .460 S&W Magnum in a semi-automatic rifle. Now take a look at the very real 45 RAPTOR.

The new cartridge is essentially a rimless .460 S&W Magnum load. It offers a serious thump for hunting hogs and other game while fitting a standard AR-10 rifle. The rimless design matches the specifications of the .308 Win, which means a new barrel and slight magazine modification is all that is needed to run the cartridge.

The genius behind this new cartridge is Arne Brennan. Brennan’s work with long range cartridges in competition shooting helped introduce the 6.5 Grendel to the shooting world. Brennan stated the cartridge works extremely well in rifles with a 16″ barrel. According to Brennan, testing had been done with other barrel lengths, but the longer barrels did not offer a significant performance increase when considering the additional length and weight in a gun that would likely be used in brush for hunting.

45 Raptor hunting

Velocity and energy levels from the cartridge are fairly impressive. From a 16″ barrel, a 300 grain Hornady XTP Mag bullet is good for up to 2300 fps and more than 3400 ft-lbs of energy. A lighter, 160 grain Barnes TAC-XP bullet can be pushed to 3000 fps.

The 45 RAPTOR compares favorably to other big bore, semi-auto cartridges:

45 RAPTOR vs Big Bore AR Cartridges

45 RAPTOR450 Bushmaster458 SOCOM50 Beowulf
Velocity2,250 fps1,900 fps1,960 fps1,900 fps
Energy3,371 ft-lbs2,404 ft-lbs2,558 ft-lbs2,404 ft-lbs

One of the features of the new cartridge is the ability to put rounds into a 6″ circle from point blank to 200 yards with no hold over.

Trajectory Comparison

Here’s a look at how flat the 45 RAPTOR is compared to other big-bore AR cartridges:

45 RAPTOR450 Bushmaster458 SOCOM50 Beowulf
0 Yards-1.5″-1.5″-1.5″-1.5″
100 Yards3″2.9″2.9″2.6″
150 Yards1.6″-0.1″0.3″-1.8″
200 Yards-2.29″-7.6″-6.6″-12.9″

Reloading for the 45 RAPTOR

Handloading these cartridges will be very straightforward using a .308 Win shell holder and .460 S&W Magnum dies. Load data, powders and bullets developed for the .460 Magnum will all work for the 45 RAPTOR without modification. Open your load book and build up your loads as normal using the .460 S&W Magnum recipes.

45 Raptor bullet

Brennan stated that the RAPTOR name will be trademarked, but he will not charge royalties to any manufacturer wishing to load ammo or make parts for the guns. (More information on this can be found here.) That means shooters will not be married to a single source of ammo or parts. In fact, other than the brass, all of the ammunition components and tools should be relatively easy to come by at local shops or online.

Initially, brass will probably be limited to a single source, but Brennan has already given Starline Brass permission to sell the brass direct and through retailers.

Pricing as of July 2022 runs between $0.60 – 0.88 each depending on the quantity purchased.

Modifying the AR-10 to Shoot 45 RAPTOR

Very little is needed to convert an AR-10 to shoot the 45 RAPTOR. The rifle needs a new barrel with a special extension, and magazines will need to be modified.

According to Brennan, some of the big bore cartridges already on the market have difficulties in feeding hollowpoint ammunition. To prevent these problems in the RAPTOR, Brennan developed a different approach to chambering a round.

For the 45 RAPTOR, the feed ramp has been moved from the barrel extension to the magazine. Brennan states this allows the cartridges to feed hollowpoint ammunition flawlessly.

AR-10 chambered 45 raptor

Magazine followers do need to be modified for the new cartridge. Essentially, the followers are shortened and an insert is placed in the forward portion of the magazine. The insert prevents the ammo from riding forward in the magazine and incorporates the feed ramp.

Standard AR-10 magazines from Lancer, ProMag and DPMS can be used with the 45 RAPTOR cartridge, and they maintain the same capacity: 20-rounds will still hold 20-rounds. Curved magazines will not work with the required modification.

Expect to pay about $300 for a Liberty Barrels stainless steel barrel and extension designed for the RAPTOR. New 20-round magazines will also be available from Raptor Shooting Systems for $39 each.

Shipping Soon

Brennan anticipates rifles production will begin in late May. He has more than 100,000 pieces of brass on hand, and another 500,000 will be delivered during the next 9-12 months.

If you have an interest in learning more about the cartridge or rifles, visit

Last Update: July 1, 2022

By Richard Johnson

Richard Johnson is a gun writer, amateur historian and - most importantly - a dad. He's done a lot of silly things in his life, but quitting police work to follow his passion of writing about guns was one of the smartest things he ever did. He founded this site and continues to manage its operation.

10 replies on “New Cartridge: 45 RAPTOR”

This new cartridge has me rethinking my position about getting an AR-10. A cartridge with a whole lot of punch, and a very nice trajectory to say 300 yards is very interesting. I’d still like to see how the uppers and ammo prices turn out.

Hi Arne,

As I understand it, the rimless design allows for the use of the stock AR-10 parts (save the barrel and modified magazines) while an actual .460 S&W Magnum would require a lot more modification to the rifle to make it work. It looks like this will keep costs down for shooters, and possibly help make this cartridge a commercial success.


Rim-lock, loading rimmed cartridges from a box-mag is a sure way to spend a lot of time clearing jams. Look up the Coonan .357, it is a 1911-inspired firearm firing the .357 Magnum. To make it work required a unique magazine incorporating an extremely steep follower.

Leaving the rim on the .460 would lead to potentially serious problems with feeding, as well as require a bolt face so large the material left to support the bolt lugs would be so sparse as to be ineffective if any was left at all.
Changing the cartridge base to the .308 Win is brilliant as it requires no specialized parts beyond the magazine alteration and barrel- the death of other cartridges designed for the AR-15 platform that required more specialized parts.
The .45 Raptor gives the entire industry a lot to look forward to.

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