[Semperfiabc]

In a nut she'll, my mini 14 cycles perfect with different brands of ammo and mags, but I put it in an ATI stock and it won't cycle. The bolt blows back maybe 1/4-3/4 of the way and sometimes not at all. The only time it cycled in the ATI was with tracer ammo I got at a gun show, it was loose ammo with no info on brand or grain. So am assuming the tracer was 62 grain or more, enough power to overcome whatever the problem is, but the 55 grain just won't cycle. In the original stock it works great. Any advice will be appreciated. It's a 581 series, has had approx 300 rounds fired, cleaned each time shot, gas port always cleaned.