I have been wanting to build an AR15 in 300 blackout for some time now. I had my mine set on a Spikes Tactical Punisher or a Seekins Precision lower, but with some of the recent advancements idk. I have seen where Rainier Arms and Mega now have a tension screws in the lower to help take up slack in between the lower and upper if it develops, but both of them are high shelf. I can not find a low shelf forged receiver that has this tension screw. Or is this screw not that big of a deal and I could get another lower without it and get an accu-wedge if there is play. I want to buy a good forged receiver, not something cheap. I also am not interested in billet, even though some of the look freakin awesome, due to the price.