Need a heavier buffer?

[calvarez]

I have a T2 and flat spring in my primary AR lower (M&P 15 MOE). The stock upper is overgassed and that combo of buffer and spring really helped. Well worth the low cost. When I put the BCA Grendel upper on it, I don't feel like it's doing anything it shouldn't, though to be fair I've only put about 150 rounds through it so far.