I shot a case of Zero +P LSWC HP 38 Special ammunition through my M66. The bullets were swaged lead hollow points and created large lead rings inside the cylinders. When I tried shooting full power 357 Magnum loads, the cases would form around the lead rings making very difficult to extract.
It was also difficult to remove the lead rings. Used torpedo brushes, got most of the rings, but used up those torpedo brushes. I do remember seeing reamers designed for the purpose of removing 38 Special lead rings from 357 Magnum cylinders. Wish I had found one.
I do not recall seeing any gas cutting rings in my M66, and I have a M586 that a buddy shot 60,000 of 38 Specials in PPC. I have not seen any evidence of gas cutting rings in any chambers of that pistol.
But who knows, maybe such things exist. I do have a barrel removed from an Anschutz action. I purchased a stripped 22lr Anschutz action from the CMP and the barrel has a ring slightly ahead of the chamber. Eddie, who was smallbore prone shooter after WW2, told me about "Eley" rings. Ammunition of the period had a high glass content in the primer. Priming compound with high percentages of glass ringed 22lr barrel just ahead of the chamber. This glass is used as a frictionator.
Page restricted | ScienceDirect I think the glass turned into some sort of molten plasma during combustion, which was good for gunpowder ignition, and this plasma condensed on the barrel steel in front of throat. That and the hot gases must been highly erosive to barrel steel. Eddie sold me a 1961 BSA Martini 22lr, he had only fired 650 rounds through, and it has a half moon ring forward of the chamber. Eddie purchased the rifle new, it did not fit him, and he put it away till I purchased it from him.
Maybe something like that happened in older centerfire primers.
After all the fun I had cleaning 38 Special lead rings from 357 Magnum chambers, I decided to shoot 38 Special level loads in 357 cases.