[alvin]

Originally Posted by Angus Magnus

My vote goes to the new barrel graft:

http://www.gunbroker.com/Auction/Vie...Item=494421202

Seller said, "I fired a single round from it, it worked".

That implies it cannot recycle correctly. This long barrel must be heavy, too much recoil energy is allocated to barrel/receiver, and too little recoil energy is allocated to bolt. If it cannot recycle correctly, that's normal. Barrel of this length is going out of range of the original design specification.