While test-fitting the Aguila 158gr .357Mag ammo in my new GP100 7-shot, I came across one round which wouldn't insert all the way. It wasn't binding with adjacent rounds, because it was the only round inserted in the cylinder at the time. It's also the only round in the box that has a problem. On closer inspection it looks like the case is deformed at the rim end: That little ridge right there is preventing the round from being fully inserted. Could this deformation have happened when the rim was installed? I've never seen anything like it before. All the other cartridges in the box are perfect.