CMMG’s Resolute 300 Mk4 is a very nicely made, dedicated .22 LR AR-15 that would be perfect for training, recreation or small game hunting. (David M. Fortier photo)
July 08, 2026
By David Fortier
Are you in need of a suitable .22 semiautomatic to take advantage of the current glut of inexpensive ammunition? Well, I have been burning up copious quantities of .22 rimfire of late through one of CMMG’s Resolute 300 Mk4 rifles—a fine-looking, upper-crust AR-15 chambered in .22 Long Rifle.
CMMG is justly famous for its .22 LR conversion kits for 5.56 NATO-chambered AR-15 rifles. These are similar to the old military conversion kits in that they include a chamber adapter and simply drop in place of the standard bolt carrier assembly. However, unlike the military kits, CMMG’s .22 LR kits are known for their reliability. Due to this they have become quite...
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