Which Superformance ? The 5.56 or the .223 ?
I have seen popped primers on carbine length gas systems.... but none from my middies... 14.7, 16, and 18"
My rifle length gas systems have no issues with it as well.
I truly suspect.. the variations in chambers and/or a carbine length gas system can cause issues when used with Superformance .223 and 5.56
FYI.. these were my recorded velocities...
.................................................................................................16" middie....................20" rifle.............
Hornady. 75gr Match....................HORNADY 223 REM...........Av. 2510 , ES 50................Av. 2640 , ES 60.........
Hornady Super. 223 Match 75....HORNADY 223 REM............Av. 2701 , ES 41................Av. 2790 , ES 54..........
Hornady Super. 5.56 75... ...........Hornady 5.56 NATO.............Av. 2785 , ES 31...............Av. 2840 , ES 42............
Data from ...
Here
My rifles like the Horn. 75gr bullets better then the 77gr....