I have decided to start a 300 AAC blackout SBR project. I narrowed it down to 2 options. I was either gonna go with a Noveske 8" upper, or with a PWS 9.75" piston driven complete rifle. If I went with the Noveske upper, I can start the SBR paperwork now on a dedicated lower while I wait for the item to ship. I am not sure how long it will take for a PWS complete rifle to ship. I cannot decide between piston vs direct impingement. One of my friends is telling me to go with the PWS because of the piston system being much cleaner with 300blk, but I don't know true this is. Can anyone with 300blk experience guide me?