CMMG came out to SHOT Show’s Range Day with a giggle switch-equipped Mk47 Mutant, and I believe we all took it for a spin. I finally stumbled up to their booth near the very end of the day, and this thing was still running strong after what I assume was many thousands of rounds. I’d chalk this up to two things . . .
First, the Mutants are designed to run AK-47 magazines. While there are now a handful of 7.62×39 mags that do function well in a standard AR-15 lower receiver, the historical success rate with this has been rather low. Feeding is better from an actual AK-47 mag, which begins its “banana” curve sooner.
Second, CMMG’s upper is designed to use a bolt that was originally their Mk3, .308 bolt. This is supposed to resolve the common issue of broken bolt lugs when a 5.56 bolt is hogged out to fit that 7.62 cartridge base diameter.
At any rate, add their SV Brake and it’s a controllable, soft-shooting 7.62×39 gun.