Re: reloading question
How many times have these cases been fired without trimming? Overly long cases can cause sticking, and pressure issues if fired. There are two different types of sizing die, neck and full length, which type do you have? Semi autos generally require full length sizing, if that is what you have make sure it is set correctly. Some rifles have tighter chambers and require a small base sizing die. Try cycling some factory rounds, if they do not have an issue, its your reloads, relegate then to the Mini 14, if they do have an issue clean and lube your AR with particular attention to the chamber and BCG.