Component installation is performed in the exact opposite sequence as disassembly, so we'll spare the details. With the barrel nut torqued to spec (anywhere between 35 and 80 ft.-lb., and wherever in this range the gas tube hole is perfectly lined up), and the new gas system in place, we installed a .300 BLK CMMG SV muzzle brake and reinstalled the handguard. After that, our conversion to .300 BLK was officially in the bag.
Component installation is performed in the exact opposite sequence as disassembly, so we’ll spare the details. With the barrel nut torqued to spec (anywhere between 35 and 80 ft.-lb., and wherever in this range the gas tube hole is perfectly lined up), and the new gas system in place, we installed a .300 BLK CMMG SV muzzle brake and reinstalled the handguard. After that, our conversion to .300 BLK was officially in the bag.

Typical of what’s available on .300 BLK ammunition are the

offerings from Hornady and Black Hills. Hornady catalogs both a 208-gr. A-MAX sub-sonic loading (1,020 f.p.s./480 ft.-lbs.) and a 110-gr. V-MAX super-sonic load (2,375 f.p.s./1,377 ft.-lbs.). Black hills offers 220-gr. OTM sub-sonic at 1,000 f.p.s./488 ft.-lbs., as well as a 125-gr. OTM super-sonic running at 2,200 f.p.s./1,343 ft.-lbs. Both of these super-sonic loads will deposit over 1,000 ft.-lbs. of kinetic energy into a deer at 100 yards.

There are basically three ways to get yourself a .300 BLK for deer hunting. Buying a complete rifle is the easiest, but most expensive route. Purchasing a complete upper for use on an existing lower is just as easy and a bit less expensive, but still represents a significant investment. The least costly solution is to replace your existing 5.56 NATO barrel with a .300 BLK barrel. That’s what we chose to do, and following is a basic “how did it.”Our host rifle was a Daemon Defense (daemondefensellc.com) OPR-15 in their new “Green Mamba” Cerakote finish, and if you have doubts about your ability to swap out an AR barrel, rest assured—it’s not rocket science. With a viceand a few relatively inexpensive specialty tools,this is a task anyone who knows what a wrench and punch set look like can tackle.

The fruits of our labor? Well, besides now having enough downrange energy to be confident in downing a whitetail, how about sub-3/4-MOA 100-yard precision? Firing Hornady's 110-gr. V-Max load, our Daemon Defense rifle and it's new Green Mountain .300 BLK barrel drilled consistent 3/4-MOA 3-shot groups, with the best pictured here measuring out at 0.70 inches. That, ladies and gents, is outstanding performance.
The fruits of our labor? Well, besides now having enough downrange energy to be confident in downing a whitetail, how about sub-3/4-MOA 100-yard precision? Firing Hornady’s 110-gr. V-Max load, our Daemon Defense rifle and it’s new Green Mountain .300 BLK barrel drilled consistent 3/4-MOA 3-shot groups, with the best pictured here measuring out at 0.70 inches. That, ladies and gents, is outstanding performance.