The 450 Bushmaster Carbine (above, top) in its factory form, is a semi-automatic AR design that uses a large .45-cal. bullet and produces recoil unlike that of the standard .223 Rem. Taming that recoil is what the author set out to accomplish (above, bottom) by simply replacing a few parts.
Bryce Towsley’s recent article concerning big-bore AR cartridges compelled me to tinker a bit more with my own, a 450 Bushmaster Carbine. I had previously changed-out the factory furniture and added a few accessories to make the rifle a bit more southpaw friendly, but nothing had been done yet to tame this Thumper’s heavy recoil—which seemed like a fun and appropriate project for this gun.
Now, .450 Bushmaster recoil is by no means punishing, but it is relatively stout compared to a .223 Rem.-chambered AR. A time-honored method of dampening recoil is to simply add weight, but as this 16″ carbine was always intended to be lightweight and handy, I made it a point from the outset to cut the recoil without adding undue extra weight. And while the host gun for this project is a big-bore, the basic principles behind these modifications should apply to any AR-15.Grizzly Gunworks Defcon 1
Starting from the front of the gun, I first replaced the flash hider with a more efficacious muzzle brake. There aren’t tons of big-bore muzzle device options on the market today, but Grizzly Gunworks offers several quality models in either thread-on or clamp-on configurations. Available in 7075 aluminum and 416 stainless steel, I selected a threaded, aluminum Defcon 1 brake (MSRP $160) for this project that weighed a scant 2.8 ozs.—only 0.4 ozs. more than the factory device. Lateral blast was, naturally, increased, but rearward push and muzzle rise were noticeably mitigated.