Rimmed cartridges & single shots

I know that rimless cartridges are regularly used in top-break single shot handguns/carbines like the T/C Encore and Contender. But would there be any particular advantage to using rimmed and semi-rimmed rounds in this particular type of action? I'm thinking not only of straight-walled rounds, but also cases like the .307 Winchester and the .225 Winchester. Would headspacing on the rim be a plus in any way?

Blunderbus

The main advantage offered by rimmed cases in single-shot actions is their more-reliable extraction. Rimless cases and weak extractors don't work well together. The extractor in a bolt action clips over the extracting rim differently, and the opening of the bolt cams tight cases loose from their clinging to the chamber walls. The extractors in single-shot or lever actions don't have these advantages.

BTW, you can make a rimmed version of any case with the '06 head dimensions by using instead .400-.350 Nitro Express cases. Use a different shell-holder, of course, but the same reamer, headspace gauges (plus the reamer and headspace gauge for the rim), and dies -- and often the same loads -- as the rimless original version.

While I am not sure what the gun, cartridge or purpose is I have a number of single shots. One is an old High Wall and they just have a conventional extractor and not a spring loaded one like the Ruger #1's that will extract rimless cartridges.

This particular rifle is in .219 Improved Zipper yet it will extract the semi rimmed .225 Winchester brass which is the same case except for the rim and neck wall thickness.

An important note is that if a rimmed or semi rimmed case can be selected that has an adequate shoulder then you can headspace on that instead of the rim. This is the same case life advantage that you would gain with a belted design.

Ken

Am not sure have not checked the figures but I think the 9.3x74R has the same head and rim dimensions as the .400-.350 Nitro, at least I had a .350 No. 2 Rigby double rifle (same case) and was told I could make cases from 9.3x74R, it is easier to get than .400-.350.

miki