From The Truth About Guns:

Over the last year, I’ve made a solidly-performing 9mm polymer framed pistol, a fun AR-15 style rifle and a great “parts-bin” AR10 in 6.5 Creedmoor based on kits from 80% Arms and Brownells. For the fourth installment of this loose series, I put together the 80% Arms AR-9 GLOCK magazine compatible braced pistol.