Hi Dogcatcher223! I have battled these short recoil problems also... good news, is that with new parts being the basis of the problem guns, all were made to cycle properly, bad news is, "There's new parts, and then there's good parts!" First of all, can you cycle the carrier all the way back with the charging handle? If you can make it catch on the hold open by doing this with an empty mag, then at least you know that if everything else is right, it will most likely work if we can just get it to travel back far enough... I have found, that when troubleshooting these types of these problems, that I could switch complete lowers, (tried 3 different lowers) of different makes, different parts, etc... and it NEVER cured the problem...(Although, I oiled the hell out of the buffer tubes and buffers!)... I believe that the problem is in one of three areas.... 1st, use of correct ammo to test the gun... XM193 Federal, Q3131A Win., Lake City M193 Ball, .... 2nd, Gas leak or restriction, in a new gun, the bolt carrier key would be about the only place it could leak, maybe the gas ring gaps lined up? I have never seen this, (the rings issue) personally make if fail, but I have been told so, and it most definitly would have an effect.... 3rd, and this is where I think the problem might be... some new uppers are pretty tight and I have found that the carrier assemblies drag on the interior of the receiver, most likely in the relief slot for the bolt carrier key... also some are tight in the middle of the round tunnel part of the upper... I have cured most of my problems in this area, by swapping out bolt carriers, and once it works, it works forever! Don't waste a shit pot full of ammo trying to wear it in. When the parts are correct, and the correct working tolerences established, it will work on the first round every time! To prove my point, if you take a dial caliper and measure the relief slot for the hammer on the bottom of the upper receiver, you will find that is is approx. .010" different from the front to the back... they were not machined this way... somewhere along the line they got squeezed a bit... The bolt carrier should run free and easy, and close all the way by just letting the recoil spring push it home... Remove the upper from the lower, run the bolt carrier in by just pushing on the back, if you feel it drag at all, that is where a potential problem exists....When all is correct, the bolt closes with a pretty smart snap! all the above is my own opinions, and experience... but, I've got most all to run.. so it's the best advice i've got to give, good luck!.... till....later...GT