I know that to have a SBR upper it has to have the proper tax stamp or to be attached to a pistol lower. My question is, is it ok to go ahead and order a sbr upper before you apply for the tax stamp or have a pistol lower . It would not be attached to a lower until i have a tax stamp

looking for the best quality ar upper for the best price?

I was seeing if anyone knew how to tighten the rivets on the upper hand guard. Mine seems to have loosened up and has a small crack in the wood by the rivet on the right side. If I push down on it I can see the front sight perfectly, but's soon as I let off it springs up.