This is very close to what I was thinking- Criterion Core 18” with matched/head spaced BCG, comp, either rifle or A5 buffer assembly/stock, and some sort of lighter weight rail. There is a dumb part of me that wants to put a 15” PRI gen3 rail on so it looks like a mix of Mk12 mod O and mod H (without swan rail). Unfortunately that would add about 6oz to the front end of the gun.