come on bullwolf post that 10mm thing again

[Lloyd Smale]

he just sent me a pm on forming 41 special or mag brass into 10mm brass that will work in a moon clip gun without clips.. Kind of like a 45 auto rim. Pretty cool stuff.

[Bullwolf]

he just sent me a pm on forming 41 special or mag brass into 10mm brass that will work in a moon clip gun without clips.. Kind of like a 45 auto rim. Pretty cool stuff.


Well I'd been thinking about this again due to all the discussion about new GP100 44 special revolvers, and the 10mm and 41 Special.

I had posted this previously in the Case Forming section of the forum.

41 Mag/Special to 10mm Autorim (http://castboolits.gunloads.com/showthread.php?315767-41-Mag-Special-to-10mm-Autorim&p=3774470#post3774470)

I'd often wondered if I could make rimmed 10mm cases for my Smith and Wesson 610 revolver.

http://castboolits.gunloads.com/attachment.php?attachmentid=53320&d=1332375253

Mostly I wanted be able to shoot the revolver occasionally, without having to use full moon clips.

In my first attempt back in March 2014, I tried to make rimmed 10mm from trimmed down 30-30 Winchester cases. It had a few drawbacks though. To name a few, I was stuck using Large Rifle Primers with the 30-30 Win cases, and the trimmed sized cases had less internal capacity, along with very thick necks and rims.

I wrote a little bit about my original attempt using the 30-30 Winchester as the parent case in this older thread.

10mm Auto Rim? (http://castboolits.gunloads.com/showthread.php?235186-10mm-Auto-Rim)

I didn't like how the trimmed 30-30 Winchester cases turned out - though they did fit the cylinder, and I could successfully set off the Large Rifle Primers in my Smith 610. I wasn't happy with the reduced internal capacity, thick necks, or being stuck using Large Rifle Primers with the 30-30 cases.

I never assembled more of the trimmed/sized 30-30 Win cases. I scrapped the whole 30-30 Winchester as the parent case idea, and went back to the drawing board.

Now fast forward to a few years later.

I decided to revisit the rimmed 10mm case using trimmed and slightly harder to form (size down) 41 Magnum/Special brass.

http://castboolits.gunloads.com/attachment.php?attachmentid=99965&d=1403162239&thumb=1 http://castboolits.gunloads.com/attachment.php?attachmentid=99964&d=1403162239&thumb=1

As I said in the previous thread, I wasn't really doing anything new that had never been done before. Others have used the same method (trimming & sizing 30-30 Winchester or 41 Magnum cases) to form the Herters 41 Power Mag which has very similar dimensions.

http://castboolits.gunloads.com/attachment.php?attachmentid=99963&d=1395218560

Since 41 Magnum brass is still precious to me, I started out with brand new unfired Starline 41 Special brass instead. This gave me a bit less case length to trim, and a Special, or SPL head stamp.

http://castboolits.gunloads.com/attachment.php?attachmentid=176430&d=1473646172&thumb=1

Trim length for me was a bit of trial and error. I ended up trimming on the longer side for 10mm (.995 inch) which resulted in perfect head spacing on the case mouth and the rim in my revolver's cylinder. Cases trimmed shorter than this would only head space in the cartridge rim. I trimmed all the cases AFTER sizing of course, giving my old RCBS case trimmer quite the work out.

http://castboolits.gunloads.com/attachment.php?attachmentid=176431&d=1473646190&thumb=1

Sizing the brass down from .435, to my target dimension of .425 took me two passes. My first pass was full length sizing a lubed case (I used Bag Balm) in an RCBS 40S&W/10mm Carbide sizing die, using a 41 Magnum shell holder.
(RCBS #30 Shell Holder for 41 Magnum/Special)

The first sizing pass got me real close, but not close enough all the way down to the case rim. Full length sized cases would not fit in the revolver yet, and showed a bit of a bulge down at the bottom of the cases.

My second sizing pass (also using case lube) was through a 40S&W/10mm Lee Carbide Factory Crimp Die, with both the crimping portion and knob removed, much like when using the Lee CFCD for bulge busting.

This second sizing pass was performed with out using a shell holder. Instead, I placed a hardwood block underneath the cases to push them all the way up into the die, until the bottom of the case rim contacts the die. Afterwards, I eject the lubed full length sized cases from the die using a rawhide mallet, and a 3/8 oak hardwood dowel to tap the cases out.

http://castboolits.gunloads.com/attachment.php?attachmentid=176432&d=1473646232&thumb=1

Doing it in this way sized the 41 Special cases all the way down to the case rim. (no bottom base sizing bulge now) The trimmed 41 Special cases now measured .426 at the base, just above the rim after the Lee CFCD sizing step.

This was a tad larger than I was originally shooting for, due to the larger Lee CFCD inside dimensions. Cases at .426 did fit easily in the cylinder of my 610 revolver after the second sizing pass so I stopped here and called it perfect. I was expecting to need to go as small as .424 - .425 of an inch for cases to fit in the cylinder.

I only made 59 cases or so (enough for me to fill up box with a few extras) as doing this was definitely a labor of love. I can easily make more later, now that I know how to perform all of the steps.

My first loading of the brass was with a mild (40 S&W level really) 180 grain jacketed load, since that what the sights are currently regulated for. It's unlikely that I will lose any of this brass while shooting a revolver, so it should be easy enough to load up box of cast 10mm Auto Rim whenever I want now.

The finished product - a rimmed 10mm case.

http://castboolits.gunloads.com/attachment.php?attachmentid=176433&d=1473646247&thumb=1

Cartridge lineup (left to right) 10mm Factory JHP, 10mm Rimmed, and 40 S&W

http://castboolits.gunloads.com/attachment.php?attachmentid=176434&d=1473646282&thumb=1

A pleasant secondary benefit using the 41 Special cases. The 10mm Auto Rim cartridges happen to fit and function nicely through my 610 revolver using HKS 57M speed loaders for model 57/58 41 Magnum Smith & Wesson revolvers.

http://castboolits.gunloads.com/attachment.php?attachmentid=176435&d=1473647619&thumb=1

At this point many of you are probably wondering why I'd use a speed loader to reload a 10mm revolver with, instead of the much faster to use full moon clips?

Sometimes it's just nice to have options. If I want to shoot just a couple rounds, or even a whole box of ammo, and not have to moon it up and de-moon it afterwards... Well I can now now.

Anyhow, there you go. 10mm Rimmed from 41 Special brass the hard way.


- Bullwolf

[maxreloader]

great info! Thanks!

[hollywood63]

Bullwolf
I tried this but for a 40 S&W revolver. I could never get the bulge out just above the rim. I used a Lee FCD with out a shell holder but it was still no go. Kinda bummed me out.

[reddog81]

The rim thickness of the 41 Special brass is correct for the headspace in a 610? Your specs show .06 for the 41 brass. I'd have thought the rim and moon clip on 10MM would be larger than .06.

I could be wrong but that was the first thing I thought of... Other than that it seems like a very ingenious project

[missionary5155]

Greetings
Thank you for posting this ! Sure gives the mind something to ponder .
Mike in PerU

[Michael J. Spangler]

Bullwolf you have some of the best ideas I've seen on this forum (even if someone else has done them before you bring them here to share the knowledge) which are always stepped up a notch by the great pictures. Awesome thread!

[Bullwolf]

The rim thickness of the 41 Special brass is correct for the headspace in a 610? Your specs show .06 for the 41 brass. I'd have thought the rim and moon clip on 10MM would be larger than .06.



A metal full moon clip for my 610 revolver measures .04 in thickness.

While a fatter plastic "Rimz" brand full moon clip was .08 in thickness.

I'd say that .06 falls pretty well between the two measurements, allowing some flexibility for larger, thinner, or even a slightly bent moon clip to still fit and function.

Most of my Starline 41 Special brass cartridge rims were .055

---------------------------

Smith and Wesson 610 revolvers also have a lip inside of the cylinder for a 10mm auto case to head space on - Just like plunking a round in a 10mm semi auto pistol barrel.

Trim a 41 Special case longer than .995 of an inch, and the longer case will start to stick out of the back of the cylinder, eventually far enough to rub on the recoil shield.

Trim a 41 Special case shorter than .995 of an inch, and it can only head space on the cartridge rim. (Like 40 S&W does on full moon clips)

For what I'm doing, think of the 41 Special cartridge rim as only being used as an extraction aid. The head space, and end shake protrusion is set by my case length.

It's possible to fire a 10mm auto cartridge (but not a 40 S&W) without using a full moon clip in a 610 revolver because of the lip. Though you would not be able to extract the 10mm auto case without using a pencil or dowel to push the case back out of the cylinder.

If you want to shoot shorter 40 S&W cases in a 610 revolver, they will only function if you use full moon clips, as the shorter 40 S&W has to head space on the artificial rim created by the full moon clip.

I trimmed the 41 Special cases to a custom length for use in my revolver. The length is just long enough to head space on the case mouth as a 10mm would, mimicking the same head spacing. My custom trimmed 41 Special cases also have the same end shake, or back of the cylinder to recoil shield clearance as 10mm or 40 S&W cases have when mooned.

If I were to lathe off the case rim, the 41 special case would still be head spacing on the internal lip inside the cylinder, and still stick out the back of the cylinder the same amount due to my trim length.

Hope that helps to clear things up.



- Bullwolf