Mark-
I've gone from 'sleeping beauty' to 'daily shooter' with 9 or 10 of my own pinfire guns and rifles, all break-open SxS sporting arms with proper period rimmed chambers (thin rims and typically shorter than modern standard chambers)
Some of these have had less-than-perfect chambers, and with the ones where things were less than ideal for very thin brass cases I just ran thicker case walls and never had to think about it again.
Chances are that your chambers were cut for thick paper cases.
The proper metallic surrogate will have case walls that will be thick enough that with loads that are anywhere within the realm of safety, you'll never have to resize them and they will never have a chance to flow or deform into chamber pits.
Did Dave note to you that he could build cases specifically for *your chambers* - did he suggest that you send him your barrels?
Can you email me photos of your 24bore pinfire shotgun, also including decent images of the chambers and bores?
I might be able to help point you to a productive solution if RMC doesn't work out for you.
I don't know if the personal messaging system on this site still works. I'll wait for your reply to this thread before I try to message you off-line.
Cheers
Tinker
