Hi everyone! I have been loading RMR 124gr FMJ RN with 4.1gr W231 at 1.135 which I have used on a variety of pistols and a CX-4 Storm. I recently picked up an AR9 with a 16" barrel and my 9mm is fragmenting out of this rifle. From what I can tell, the only possible difference between the CX-4 and this AR9 is the barrel twist rate. I think the CX-4 has 1:16 while this Ballistic Performance barrel may have 1:10.
The ammo passes the plunk test on the AR9 and spins freely. No issues with cycling, feeding, ejecting, etc.
I’d like to continue using 124gr FMJ. Do I just have to slow it down?