I've been kicking around what I want for my first SBR. I have an existing lower build I plan to use. But my desire is something different in caliber. I have two pistols 223/5.56 and a 300 BO. So I'm thinking 6.8SPC II for this SBR. With existing parts all I need is a barrel and bolt. I've a 6.8 carbine and love that round. Any haters as far as using a 6.8 on an SBR? Bison Armory 11.5" barrel with a carbine gas system will complete and SBR for less then $300 using on hand parts. Is it a problem if I have all the unassembled parts in my possession before having the stamp?