Thanks for the info> OK from what I have seen from pictures (since our parts kits are on the way and I have not seen an actual trunnion yet) the Pictures showed me areas cut out in the trunion for the rivets so the barrel clears the rivets. Correct me if I am wrong but what I am thinking is grinding down the rivet head so it is just below flush with the cut out area of the trunnion so the barrel can be put in with out being impeded. Make my tool to hold the rivet head in place. Then set up tool and hammer (TAP) the other end of the rivet to get it started and finish it off with the rivet tools to make a head on them. My friend bought some bulk boxes of USA made rivets. ( Yea I know they are not metric) We will use the right size drills to take care of that issue. That way we got some extra rivets to practice with to get good formed rivets before we do the build.