Well I’ll be darn. This brings back memories because in the late 60’s I was at a gunshop and the owner showed me a Browning trap gun (not a Citori) bottom barrel which had this rippling effect inside on the bottom at of that barrel. He said it was caused from loose shot. I always questioned his explanation for this, but I guess he was correct. Periodically I have thought about this condition, but you have now confirmed it. Thanks.If it is a real thing, open crimp allows shot to rollout. As long as barrel is level or up, shot will remain in barrel. Next shooter elevates the gun and perhaps has a barrel upward hold. Loose shot sitting against the mouth of the shell. Gun is fired. Shot in the shell pushes crimp out, over the top of the loose shot and as shot load exits the shell, it runs over the loose shot and pushes downward on it exerting force on the inside of the barrel.
This is why I so anal about worn shells. If the crimp is weak, I toss it, I don’t seal it with candle wax or masking tape like some do. Wasting 11 cents worth of shot or ruining a gun barrel is not worth using a hull 15 times that has a value of less than half a cent.Well I’ll be darn. This brings back memories because in the late 60’s I was at a gunshop and the owner showed me a Browning trap gun (not a Citori) bottom barrel which had this rippling effect inside on the bottom at of that barrel. He said it was caused from loose shot. I always questioned his explanation for this, but I guess he was correct. Periodically I have thought about this condition, but you have now confirmed it. Thanks.
Then it is not a real thing or a problem.If enough shot was loose in the barrel to affect the crimp opening and the crimp was that weak, it would be a really low pressure blooper. AT that low pressure, in my opinion only, it would not have an effect on the barrel. That area prior to the forcing cone and the forcing cone itself would be a very strong area of the barrel.