As my username implies, I'm an avid fan of the 10mm Auto cartridge.

I was recalling the parent case of the 10mm as being a .30 Remington. Jeff Cooper et al cut the .30 Remy to a length that would fit in the 9mm size guns and they didn't like the performance so they cut one down longer to the OAL of the 45 Auto.

I was thinking of doing a similar thing with the .30 Remington and 10mm by cutting off the case at the shoulder, making it a straight wall like the 10mm is, and stuffing a 10mm bullet in it. For a TC Encore pistol.

Thoughts?

quote:

I was recalling the parent case of the 10mm as being a .30 Remington. Jeff Cooper et al cut the .30 Remy to a length that would fit in the 9mm size guns and they didn't like the performance so they cut one down longer to the OAL of the 45 Auto

I had understood that the case was cut to the 10mm length and was chambered in the ACP length actions along with the 38 Super. Then shortened to fit the 9mm length as the 40S&W. But I have been all wet before.

As to your original question.
Loadtech lists the following 10mm case lengths.
10mm .987"
10mm Magnum 1.22"
10 OTTR 1.66"
10 Suger Magnum 1.945"

Distance to the 30 Rem shoulder is 1.498". So I would say the last two simply opened the neck up.

post your criteria and design parameters first.

Expectations: "X" velocity with "Y" grain 10mm bullet

Platform: Encore Pistol

Alternate plan: use the cheap 38-55 case and just expand the neck from .379" to .400" and shoot it full length.

Rich
DRSS
Knowledge not shared is knowledge lost...

quote:

Originally posted by ramrod340:
I had understood that the case was cut to the 10mm length and was chambered in the ACP length actions along with the 38 Super. Then shortened to fit the 9mm length as the 40S&W. But I have been all wet before.

Part of the forgotten history in the 10mm's development was they borrowed the .400" bullet from the 38-40 WCF and started with the 9mm size platform. It wasn't the performance they were looking for so they stepped up to the next platform size, the 45 Auto. They liked what they saw so they gave it the nod.

Essentially, they created the 40S&W before there was even a 40S&W but said it wasn't good enough.

quote:

10 OTTR 1.66"
10 Suger Magnum 1.945"

Distance to the 30 Rem shoulder is 1.498". So I would say the last two simply opened the neck up.

So these last two are a simple .30 Remy necked up to 10mm?

quote:

post your criteria and design parameters first.

Expectations: "X" velocity with "Y" grain 10mm bullet

Platform: Encore Pistol

Alternate plan: use the cheap 38-55 case and just expand the neck from .379" to .400" and shoot it full length.

Expectations: Designed for a 200gr bullet operating at 37,500psi chamber pressure. Max OAL not to exceed 2.250".
Platform: For prototype/load development an Encore pistol, perhaps 10 inch barrel. If all goes well, will get an AR15 made up (hence the max OAL of 2.260"-to fit in mag).

I'll have to study the 38-55 case more. That's a low pressure round from the blackpowder days, right? I want 10mm-ish pressure or slightly higher.

Don't know much about wildcat design, that's why I'm asking.

quote:

Part of the forgotten history in the 10mm's development was they borrowed the .400" bullet from the 38-40 WCF and started with the 9mm size platform. It wasn't the performance they were looking for so they stepped up to the next platform size, the 45 Auto. They liked what they saw so they gave it the nod.

Essentially, they created the 40S&W before there was even a 40S&W but said it wasn't good enough.

OK I'll take your word for it.

I would assume the longer two simply have the main body taper continued.
I would check on these two sites if you haven't already.
http://www.ottllc.com/
http://tcbunch.com/home/index.php5?title=Main_Page
http://specialtypistols.infopop.cc/groupee

My question is where are you going to get 30Remington cases?
Because last I checked they aren't generally available.

Or are you going to start with 6.8SPC cases?

AD

I'm a Type 06 FFL. I can go factory direct for components.

Graf's has Remington brass in stock.

If I went with 6.8SPC cases, it would take a number of steps to neck it up. .277 to .400 is a big jump.

Nice thing about working with the .30 Remy case is adaptation to an AR15 requires the spec barrel, gas tube, and I can just use a 6.8SPC bolt.

If you can "go factory direct" I'd try to aquire "basic brass"
that doesn't have the shoulder/neck formed.

AD

Might be doable.

Also entertaining the idea of necking the 10mm Auto down to .257", sort of like a .256 Win Mag but in a 10mm case. Would be built on a 1911. Trying to form brass but I think I need to get a 25-06 or 250 Savage sizer die and cut it down so the case will fit and I can form the neck and shoulder.

I have a .256 Win Mag set but that didn't work. I can take the 10mm case down to .30cal no problem with a .30 mauser die (I form 256 Win Mag from 357 by running in a bit in the 30 Mauser die, then in the FL 256 Win Mag die) but the 256 Win Mag FL sizer is too long to form the neck and shoulder.

The 308/30-06 family will have enough room in the body section to fit the 10mm case so I just need the die to form the shoulder and neck. Trying to make a dummy to try and hand cycle in my 1911. If it works, just a reamer and dies and I'll be set. Will have to have a barrel made up for my 1911, which is in 10mm. Just a barrel swap is all it will take. Basically like the 9x25 Dillon but only .25 caliber.

Since it's for an encore wouldn't it make more sense to use .30-30 cases?

Load data and initial ballistic testing will be in an Encore but I also want it to run in an AR15, so a rimmed case is out, unless I turn down the rim, which essentially creates a .30 Remington. I don't have a lathe so I'd have to use a bench grinder.

I too like the 10mm. Got my Mod. 20 Glock out of lay-a-way the day I turned 21 (a long time ago.

Sounds like what you are talking about is an elongated 10mm MAG. I guess this round would be a 10mm MAX. BTW whatever happend to the 10mm MAG round?