Yes.

Yes. The Magpul PMAG Gen2 MOE 5.56 30rd magazine will fit and function flawlessly in the American Tactical Alpha Maxx (Ria) AR, as both adhere to the standard AR-15/M4 mil-spec pattern.Because standard AR platforms follow universal geometry, you are not locked into proprietary magazines. This specific magazine offers a highly reliable polymer construction and anti-tilt follower that work perfectly with your rifle.

Hi Michael, yes sir, the Magpul PMAG Gen2 MOE Black 5.56 30rd Magazine will work fine in your American Tactical Alpha Maxx Ria AR 5.56 NATO
Stay safe & have a great day!

Hi Michael and welcome. Yes, they will fit and function, no issue. That said, I prefer the fit, function and drop free capabilities of the Gen M3 which were slightly redesigned with improvements over the Gen M2's. Cheers, stay safe and enjoy!

Yes — the Magpul PMAG GEN M2 MOE Black 30rd 5.56 Magazine should fit and function properly in your American Tactical Alpha Maxx / Rock Island Armory AR chambered in 5.56 NATO, assuming it uses a standard AR-15/STANAG magazine well. The PMAG Gen M2 MOE is specifically designed for AR-15/M4 platforms in 5.56 NATO/.223 Rem.