Want to Shoot the Mighty 450 SMC Cartridge? No Problem with CMMG’s GUARD

For those unfamiliar with 450 SMC, Triton first conceived the cartridge in 2001. The design was ultimately taken over and completed by DoubleTap ammunition years later. In essence, it is a magnum version of .45 ACP that offers ballistics that are comparable to 10mm. It is a true “stopper” that delivers energy capable of taking down big game.

While the 450 SMC uses a case with the same outer dimensions as .45 ACP, there are a few significant differences that allow DoubleTap to load 450 SMC with five to six thousand pounds per square inch of pressure more than a standard .45ACP. First, the 450 SMC uses a small magnum rifle primer instead of the large pistol primer. This modification allows the hardened case to be thicker at the base.  Second, the brass is manufactured from the ground up to handle up to 30,000 pounds of pressure. The result is a dual-purpose cartridge that is exceptional for both hunting and personal defense.

While 450 SMC can be safely run in any .45 ACP that is rated for +P ammunition, the amount of rearward force created by such a hot load would potentially be problematic from a straight blowback AR15.  CMMG’s GUARD platform can overcome these issues, however, thanks to the Radial Delayed Blowback operating system.

The Radial Delayed Blowback system uses up some of the recoil impulse of the spent round to unlock the rotating bolt from the barrel extension. This mitigates the leftover rearward force that then drives the carrier back to cycle the action. By eliminating some of this rearward force during the unlocking sequence, the GUARD requires less weight in the bolt carrier group and buffer to safely cycle. This reduction in reciprocating mass results in less felt recoil for the end user.

Here’s how the 450 SMC stacks up against 10mm out of a 16-inch barrel (data provided by DoubleTap Ammunition):

450 SMC
DOUBLETAP AMMUNITION	MUZZLE VELOCITY	MUZZLE ENERGY
450 SMC 160gr. BARNES TAC-XP LEAD FREE	1740 FPS	1076 FT LBS
450 SMC 185gr. BONDED DEFENSE® JHP	1725 FPS	1223 FT LBS
450 SMC 230gr. BONDED DEFENSE® JHP	1400 FPS	1001 FT LBS
450 SMC 255gr. HARDCAST SOLID ™	1300 FPS	958 FT LBS
10MM AUTO
DOUBLETAP AMMUNITION	MUZZLE VELOCITY	MUZZLE ENERGY
10MM 165gr. BONDED DEFENSE® JHP	1700 FPS	1059 FT LBS
10MM 180gr. BONDED DEFENSE® JHP	1600 FPS	1023 FT LBS
10MM 200gr. HARDCAST SOLID™	1590 FPS	1123 FT LBS
10MM 230gr. HARDCAST SOLID™	1350 FPS	931 FT LBS

CMMG Lifetime Quality Guarantee

CMMG, Inc. will guarantee its products against defects in material or workmanship. CMMG, Inc. will repair, replace or substitute part(s) (at CMMG, Inc. discretion) at no charge to the customer if a defect of material or workmanship is found. All service work must be carried out by CMMG, Inc. The warranty applies to the original purchaser and a copy of the invoice or proof of purchase must be provided when submitting for service or work.

About CMMG:

CMMG began in central Missouri in 2002 and quickly developed into a full-time business because of its group of knowledgeable and passionate firearms enthusiasts committed to quality and service. Its reputation was built on attention to detail, cutting edge innovation and the superior craftsmanship that comes from sourcing all their own parts. By offering high quality AR rifles, parts and accessories, CMMG’s commitment to top-quality products and professional service is as deep today as it was when it began.