I once snapped the handle off of an antique 12ga priming tool after using it just a couple times. I don't know if this will help any, but here's how I do my 12ga Rem-UMC shells. I place the empty hull over the primer on a flat table top and push it down to get the primer just started, or "stuck" in the pocket. Then I set it in my Lee LoadAll 2 to seat the primer. But before I had the Lee, I would put a socket driver (5/16" I think? Large enough to fit down in the bottom without pushing on the primer pocket). Then tapping the end of the driver handle with a hammer to push the hull down over the primer. I recall someone once saying they had primers go off when trying that, but I did hundreds with no problem. If the primer pocket in your shells is actually too small for the primer to even get started, then I guess that needs to be addressed first. Good luck.