, I just ordered my 16" upper yesterday. I originally was building a 556 upper but they had to go and put this on sale again..I have a rock river lower w/6 position stock(magpul) but i still need a buffer & spring, from what I read the heavier the better. I was woundering if anybody tried the spikes ST-SST - 7.0 oz. buffer? if not what would work best. Needless to say I am stoked about getting this together and plan on perusing here quit a bit...
