10mm & 40 S&W Rimmed

[hollywood63]

I was reading a post on another forum and there was reference to a wildcat cartridge call 10 mm RMS where you take a 41 mag case and size accordingly to shoot in either a 10mm or 40 revolver.  I have looked and found something on ammo guide but I can't get registered for some reason.  Does anyone have any info on such a critter?

Thanks

[The_Shadow]

There was the G&A 40 and G&A 40 Magnum and the 401 Powermag by Herters and Randy Shelley messed around with  rimmed version of the 10mm as well.

http://www.thegunzone.com/brenx/40ga.html

https://en.wikipedia.org/wiki/List_of_handgun_cartridges

https://www.shootingillustrated.com/articles/2011/7/21/herters-401-powermag/

[DM1906]

Don't know why you can't get registered. I've been a member there for years. Send a message to Mike Haas (site owner). He'll get it covered.


Bob Shell submitted this "10mm Auto Rim RMS" to Ammoguide:

I designed this cartridge as a result of a special request. My customer owns a S&W 610 in 10mm Auto but doesn't like using the required moon clips.  So I designed a rimmed version of the 10mm based on the .41 Remington Magnum case.

I've done this and it works well in my Ruger. Resizing was simple. Trimming to length and neck turning took the most time. The brass is thicker and messes with pressures (reduced case capacity), but that shouldn't be a problem with the revolvers. I did have to lap the case heads some before they would function. That may not be an issue with a 610 or other wheel gun that doesn't head-space off the case mouth.


(This is intriguing)
Paul Stephens submitted this "10mm Rimmed Magnum" to Ammoguide:

Based on the .375 Winchester series of cases, the 10mm Rimmed Magnum is a potent handgun wildcat developed by Paul Stephens. Currently chambered in single-shot pistols,  Stephens is now evaluating revolver frames to determine the best candidate for a prototype, but remains open to alternatives, admitting he may have to "...learn how to make a revolver myself..."

As the round is in no way related to the well-known 10mm Auto cartridge, Stephens  has had to be creative to produce functional firearms. He modified a .375 Winchester reamer from Clymer for the chamber and then uses an adjustable straight reamer to finish the bore of the chamber.

Relates Stephens, "...I have loaded 200 grain bullets with a 12 inch barrel and get 1545 FPS and hunting accuracy..."

[DM1906]

Keep it simple. If you only want to shoot w/o moon-clips, or with a case mouth head-space revolver (to shoot .40SW in a 10mm cylinder). Slip an O-ring into the extractor groove. Viola! Instant rim. I spent some time modifying E-clips to do this, then it dawned on me. I was doing it wrong, and making work. The O-ring idea came to me in a dream. (I dream about gun stuff. Nuts, huh?)

BTW, the unmodified E-clips work fine in a 610, and would probably work in any revolver that uses moon-clips (the RBH cylinder to breach gap is too tight). I can look up the size and/or part number, if interested (I'm sure I wrote it down, somewhere....).