P14, knock yourself out with the OAL. Man, nothing cranks you off more than a gun that aint running! I would try some different OALs, load up dummy rounds and hand cycle them through the gun. I tried oal of 1.135 regular length and my 1.180 oal with the same powder charges with weveral powders. Difference was about .02gr of powder with NO accuracy change at 50 ft. benchrest.
Now, I am wondering if your feeding problem is gun related? Does regular 1.135 oal .40 rounds function 100% in your gun? If not you will need to check your extractor tension and your recoil and magazine springs. Believe it or not, ext. power mag springs will screw up your gun when you are shooting light loads, been there done that! Lots of variables. If the gun runs with factory ammo 100%, then you will have to tune the gun(ie. springs). Another thing to look at is the profile of the bullet. Some are more feed reliable than others. Lots of things to play with. Good Luck, hope some of this helps. DC
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front sight is good, front sight is good!