Purchased 2 Tactical Innovations mags with the polymer lips, set the screws as instructed. Put in an exact edge extractor it works great, but the mags still FTF every couple rounds even with stingers, tried Winchester H/P 1330 had better luck. Going to try Federal H/P 1260 from Walmart next. Bought a Butler Creek steel lips, the bolt wont even cycle, looks like the lips are too high. Dont know what else to do. Maybe its the polymer bolt buffer or the Tactical Innovations bolt handle?