Shell holder not working

[ElevenBravo]

I'm having a problem fitting brass into my shell holder. Originally when I started reloading 45-70, I bought a RCBS #14 shell holder and a couple of bags of Winchester brass. Immediately I had issues with the cases fitting into the shell holder. I bought a new RCBS #14 holder and things were OK for a while, and figured I managed to get "that one" that somehow got through QA. With the second shell holder, I ran through 300-ish rounds with no issue, using new, once, and twice fired Winchester brass.

Now I'm trying to reload some brass that I loaded on Thursday and fired on Friday. I loaded 50 rounds with no issue, went to the range and shot 41 rounds. Trying to reload today, most of the brass will not fit into the shell holder that they fit in 2 days ago. I pulled the 9 rounds that I didn't fire and tried to press them into the holder and most aren't fitting either. I'm at a loss to explain how a piece of steel can suddenly not work anymore. I don't have the tools to grind the inside lip of stainless steel, but the holder is currently sitting in my meat freezer to see if it will shrink.

I've measured the rim thickness of a sampling of the brass I'm using and it's between .065-67. No visible burrs on the rims, and none of the brass I'm using shows any sign of overpressure (using 40.1gr of IMR4198 ). Outside case diameter where it meets the rim is .500 exactly and the width of the channel on the shell holder is .518


Any idea what's going on and how to correct this?

EDIT:

 

[TexasOutlaw]

Have you tried cleanig tje shell holder? I'm not trying to be a smartass but that has happened to me before. If there is any trash in the groove it won't settle in the holder.

 

[Moonpie]

Clean the inside ring/groove on the shell holder.
Probably has some gunk built up in the groove.

ETA: Check to see if there might be a burr on the opening to the groove on either side. Use a needle file to remove.

 

[TheMailMan]

Try a RCBS #6 shell holder.

 

[Dawico]

Try a different brand of holder.

Freezing the shell holder will probably make it worse. Heat it.

 

[TexasOutlaw]

Winchester brass is soft. Check and see if the rim of the brass has been bent from ejection!

 

[TexasOutlaw]

Also look and see if the primers are seated well or have backed out.

 

[ElevenBravo]

Just heard back from RCBS, they asked for one of the shell holders and some sample brass. Their people say that my press is crushing the shell holder and to adjust the sizing die so that it touches the shell holder and not do the additional quarter turn.