Took my R51 and two boxes of Monarch 115 gr. ammunition to the range. First round failed to chamber properly. After seating it still didn't "feel" right. So I dropped the mag and went to eject the round. It wouldn't eject. Slide was locked up.
I've seen this before with some of my hand-loaded HC and Coated HC bullets. The ogive of the bullet was engaging past the leade of the chamber. The bullet was engaging the rifling, basically. Bad juju. I braced the rear sight on the wood shooting table. I love the rear sight on the R51. When I finally managed to eject the round, I found that perfect scuff mark ring on the ogive. I fed a box of the Moarch to my Sub 2000, which has a looser chamber and is blow-back anyway. I pulled out some of the last remaining hand-loaded bullets I have that don't cause chamber problems. The were from SNS Casting, but they've discontinued that mold and started something else. While they don't over-pressure the gun, the loaded cartridges don't feed well.
Most of the time, factory loaded cartridges are fine but I have to be super careful and "pre-test" them before I run them.
I know that having a SAMMI minimum spec chamber theoretically makes the gun more accurate but it truly is one of the most frustrating things about this gun.
Peace favor your sword,
Kirk