Having issues with my 11-87 premiere. Just got it a little while ago and just really started using it quite a bit now for the bird hunting season. It's having trouble with the 7 1/2 shot loads. It's not taking the spent round out of the barrel or it's kicking the round out and the bolt is staying open. I cleaned the gun thoroughly, just wondering if the gas system isn't designed for lighter loads or if something else might be the issue like the o-ring or something. Any thoughts. Also the gun was used, also it was dirty as hell and left in a safe for about 5 years. Let's just say it was pretty nasty before I cleaned it.