Guys, I am building an AR pistol currently and looking for a decent priced, yet quality upper. I already have a spikes lower all done just need help on a couple things. Buffer tube, buffer, spring etc... : I have a spikes buffer and spring, is the pistol version different? Upper : I'd like to do a 7.5" upper with a free float quad rail. Looking at some YHM complete's that look nice. Any opinions on these or suggestions on other brands? As always, I greatly appreciate the input and help from the members here.