You said these were new steel shot shells? The reason I ask, is that I shoot trap and have seen guys struggle ejecting low brass shells with their pump guns, and autos when the re-loads they were shooting weren't sized. Guys who shoot trap with their nice singles and over-unders have their chambers over-bored so they can shoot re-loads without sizing their shells every time. If your not familiar with re-loading, sizing means to compress the brass to it's original dimension as if it was factory new. I can speak from experience on this, every time you shoot a shot shell, the brass expands a little every time, and maybe that's what is happening to your shells new or used. I believe I read that you were shooting remington brand shells, and I shoot that perticular brand in that perticular size flawlessly out of my auto, so it leads me to believe that you may have some sort of gun problem. As stated previously, a minor imperfection could cause havoc. A burr in your chamber smaller than a grain of salt could be enough to cause your problem.