I definitely need to check lengths. Maybe some of you can help me out.... I first want to know what the weight of the buffer is. Is it a standard ar15 buffer? I was under the impression it is a "carbine" buffer, but proprietary to s&w? Theres some confusion to that. Anyway, my buffer seems to be heavier than my ar15 carbine buffer, but havent weighed it. Next, the length of the buffer spring. Next the length of the s&w spacer.

Are your guy's actions really stiff (difficult to charge)? I mean even after lots of lubing, when that spacer was in there, it was pretty darn stiff. Like i think i need to work out more stiff. Even doing simple things like press-checking was unusually difficult. After spacer removal, while still stiffer than a standard ar15, charging the gun felt much smoother. I can do press checks w/o holding it against a body part.

I did check gas alignment with compressed air and it was gtg.

I will say that the only ammo that runs well is black hills 168. Out of 60 rds, i only had 1 or 2 short stroke failures. Whereas, federal gmm 168 had 3 ss failures in only 20 rds. Ppu 168gr does no better than ppu 145gr as far as failure rate. Whats really weird is that sometimes i only get a couple failures the entire range sessions even shooting the 145gr's. Then the next day, they fail almost every other round it seems like. What really put it over the edge was with the freedom munitions 168gr rds as they failed constantly with a-max's ftf rate 1/1.

Again, even when its not short stroking, the round fires and i can feel a slight delay in the cycling even when it does pick up the next round. When it short strokes, the delay is even more noticeable. Kind of like "BANG-CYCLE" when its supposed to be like "BA-cycle-NG".

It really does look and feel like the buffer system is dicked up in some way. Either the spring is too stiff, too long, or the buffer is way heavier than it is supposed to be. Every other person who experienced short stroking issues in their m&p that i read short strokes only with nato rds or pretty much any round 150grs or less. As soon as they run heavier gr bullets, their problem goes away. Not mine...