I have a 8 inch SBR 300 blackout barrel from ballistic advantage on one of my SBR builds. I also have a Syrac Ordinance piston on that build. I cant get supers to cycle the action unless they are suppressed. All of my hand loads keep short stroking on every USGI mag I have. It will sort of hold back on my lancer mags but not well enough for a mag change. I have ruled out misaligned gas block, buffer springs, buffers, and magazines as the problem. The only thing left is the port size on the barrel. I don't think its getting enough gas to move the piston far enough. Ballistic advantage even states that the port may need to be opened up for pistons. Does anyone know the optimum port size for a Syrac/Superlative piston on an 8" 300 blackout barrel? I have read the optimum sizes for DI systems but have yet to find anything for a piston. I am going to open the port but I really want some advance from someone that has done it before I start.