JR's are very picky about ammunition and it may get progressively worse with .45acp, I think they haven't made the eject port big enough for reliable ejecting. It does not like hot loads so you may need to test a whole wack of different ammo and different weights too and see what it likes or not. If you reload, build a little reduced load and give it a try, using different powder/primer combination also makes difference.. Most of the problems occur during feeding, it basically jams in 60 or so degree position in respect to the axis of chamber, my findings are, for one, your magazine needs to be top notch quality, preferably OEM Glock, second,hot load seems to generate a more powerful blow back that causes the next round to feed improperly. Also, they come very often from factory pretty much dry so you need to take it apart, clean it up and lubricate it well with good gun oil, especially the firing pin inside the bolt but don't flood it, just oil reasonably. Last, they seem to behave atrociously for the first few hundred rounds and then they break-in and settle and run much better. Hope this helps
