I have been researching the AR pistol to figure out what works & what don't before I spend money. Palmetto state armory has a 12" upper with complete bcg & charging handle for $400.00. Anyone have experience with their short uppers on a pistol lower ? Any tips on what buffer tube would ensure proper function of this length pistol ? I will eventually go through the proper steps & make this a SBR but for now want a pistol. I know there has been some discussion on how bad Palmetto state's bcg's are but that can be changed. All advice is appreciated.