I actually got my calipers out and the rivets are aligned from the center points. There is a 0.020" difference in the width of the feed lips from the front to back. I think my problem may be my reloads are hotter and I have a higher cyclic rate, they were worked up in a 1911 and M10/45 and I think are too warm with the longer Thompson barrel. I have some blazer brass I need to dig out and try next outing and maybe get some S&B. I am shooting in a 1928AC I have had since late February. It performs flawlessly with any stick mag I have tried and the Taiwanese L drums. http://i379.photobucket.com/albums/oo240/Sandlewood_3/Mobile%20Uploads/20170706_180046_zpsanroed7r.jpg http://i379.photobucket.com/albums/oo240/Sandlewood_3/Mobile%20Uploads/20170706_180404_zpsa8tegtvm.jpg Here is the greasing tool I made for cheap with a 1/2" pvc end cap and 6mm zerks with a cheap drill bit / tap set from Amazon. If I have to grease again I'll sand the top of the cap down to make a flat spot for more reliable clamping, but it worked for the 2 L's and 1 C I needed to grease. http://i379.photobucket.com/albums/oo240/Sandlewood_3/Mobile%20Uploads/20170706_180222_zpsbux9rczi.jpg