Took a look at the Wilson Combat 6.8 uppers.

Holy cats $1,250. I could by two M&P sports for that much. I think I'd be more interested in building a new upper.

What is the difference between the SPC II chamber and the ARP chamber? Looks like I can get a barrel for a little better than $200.

Any sources for some of the parts needed? Bolt, mags, barrels?