My target and varmint rifles are single shot. When varminting, I carry my ammo in those nice blue Lapua ammo boxes in which their brass is shipped. In a hurry to fetch a case, I have had the rim of a case hang up in the top hole and have dumped half the box! We chamfer our case mouths for ease of flat base bullet insertion. The edge of the underside of that top hole can be chamfered such that the rim of a case will not get caught. I bought a Sinclair case mouth deburring tool holder(made for Forster and Wilson deburring tools) and inserted a Forster case mouth deburring tool(chamfer) and put it in my drill press. After adjusting for depth of cutting, I chamfered the inside edge of the top opening of these boxes...no more problem. If nobody else has this problem, ignore my post.