I used to work the Great Western Gunshow in Pomona, Ca. We sold parts to Tanker guys all the time. The Fed Ord guns were poor at best. They chewed up parts like crazy. Most(?) were "re-welds" and just would not run right. Fed Ord sold them cheap and guys bought them like crazy. I would find a CMPicon receiver and replace the Fed Ord receiver. Good luck with the project.