Brownells published a video in which host Caleb reviews CMMG methods that let an AR-15 shoot .22 LR instead of costly 5.56 NATO. One method is the Bravo kit that drops a blowback rimfire group and adapter into the existing upper and uses special magazines. The other is a complete upper with a barrel designed for rimfire, which Caleb prefers when owners shoot often because it can group better and keeps residue out of the centerfire parts.

Caleb cites rimfire prices near seven or eight cents a round. Earlier AmmoLand tests of the Bravo kit across three AR-15s totaling 600 rounds showed groups near 1.6 inches at 50 yards.