I bought 2 used MKIII barrels from a guy on the RFC forum.
Stainless Steel MKIII conpetition target barrel/receiver $100
Blue MKIII 6 7/8 target the one with adj sights and heavy tapered barrel $50
Put them on MKII frames put red dot on the CT and 4 X burris scope on the Blue one.
Both shot excellent with Wally World Fed bulk pack.
I'm happy.........

You never know if they are keepers until you shoot them.