Using 10mm Auto brass for .40 S&W loads?

[gmerkt]

Turning this thing on its head, having a 10mm handgun, then dialing it down if desired is a better situation than trying to bump up a .40 S&W. I have owned a number of 10mm autos and revolvers and always appreciated the wider ability to tailor loads. If I had a .40 and was not satisfied with its performance, I'd think about getting a 10mm. The .40 is more of a duty cartridge, and lacks the versatility of a 10mm that reloaders can enjoy.

 

[Member 24198]

Have araka test it for you.

 

[whiskeybill]

In a past life I recycled 6.5 x 55 rifle brass into 45ACP silly+stupid+super-heavy. Look it up, the base is close enough.
True the case thickness necessary to protect the unsupported portion of the case (ramp and throat) reduced powder capacity. The addition of a maximum cartridge length for magazine due to the heavier-longer projectile also reduced case volume.
As you develop loads with reduced volume the amount of powder that produces maximum velocity without pressure becomes critical.
I'm a big fan of lightly compressed loads but here the faster powders wouldn't quite fill the void and were inconsistent unless they did fill the void and it all seemed to happen at once. Case head separation, loose-smoked-punctured-even falling out primers. The switch to rifle primers saved the primer but not the pocket.

In the end it was red or green dot and an experiment with 'clays. I'll not offer the loadings because , well, I do have a conscience even if you don't.
So if I can use rifle brass to propel 350gr+, flying ashtrays, out of a 'O" frame Colt at 650 Ft/sec it shouldn't be that far a reach to go from 10mm to .40S&W.

I do go on but for my 1911 brethren, do any of you remember a brief period of time where experiments were dome with incrementally longer cases for a variety of reasons? Some of the reasons were accuracy ie, sharp shoulder and deep seated bullets with minimal throat, higher pressure lighter rounds , and my favorite the silly heavy. I believe the case lengths were around .920-.940". (not the rowland @.957)

Why 6.5x55 brass? The case head dimensions of the 45 Auto are the same as the old 30-'06. Same rim diameter / thickness. The Swede is a bit larger in rim thickness / diameter. Not by much, but '06 brass would have been my choice due to availability and cost. Of course, I own a couple Swedes, and brass can be scarce and expensive on a good day.

 

[Koda]

I was thinking along the lines of +P or +P+ loads for .40 S&W.

What is the pressure limit of a +P and +P+ in .40S&W?

 

[JDubDub]

Some interesting theories in this thread. Re the small primer vs lg primer making 40 brass stronger, some 10mm factory loads are now using small pistol primers. The original 10mm load used small rifle primers, but switched over to large pistol primers. The construction of the gun, including the weight of the recoil spring are going to have more of a difference on the max pressure of a specific load than minor changes in the brass. Brass is mostly there to act as a gasket.

But if anyone wants to try their luck, I have a few 5 gallon buckets of 40 brass. I'll be happy to trade a bucket for 500 rounds of 10mm brass.

 

[orygun]

I was thinking along the lines of +P or +P+ loads for .40 S&W.

Also wondering it outfits like Buffalo Bore, Double Tap, et. al. might use shortened 10mm brass for their +P loads - probably not though.

Kind of an academic issue as the only .40 pistols I have are aluminum alloy and repeat use of really hot loads isn't good for them. If I had a SSE P226 in .40 then that would be a different.

Unless shooting in a gun with an unsupported (partially supported) chamber, I'd say the case strength is the least of the concerns.
If shooting in a partially supported chamber, I'd say it could prove beneficial in the long run if running hot loads, at least as far as case life goes.
Pressure will also be raised by a case with the thicker web and smaller chamber, so +P and +P+ loads will require less powder to reach the same pressures.
It's nothing I'd be afraid of. But it's nothing I'd bother trying in the first place.

 

[orygun]

But if anyone wants to try their luck, I have a few 5 gallon buckets of 40 brass. I'll be happy to trade a bucket for 500 rounds of 10mm brass.

And this gets right down to "it". Why waste valuable brass in a gun instead of the correct brass which is commonplace?
You won't see me cutting 357 Magnum brass down to use as 38 Special.

 

[arakboss]

And this gets right down to "it". Why waste valuable brass in a gun instead of the correct brass which is commonplace?
You won't see me cutting 357 Magnum brass down to use as 38 Special.

"You won't see me cutting 357 Magnum brass down to use as 38 Special."

I had that idea once, but then it was suggested that 38spl and 357mag brass construction are the same except for length. I never could find a definitive answer on that. Subject was moot because the Astra revolver I have, ended up not being the 38spl revolver capable of 357mag pressures.

 

[gmerkt]

The bigger question I guess is: is 10 brass scarce or expensive compared to 40?

This ^^. .40 brass is way easier to get than 10mm and usually priced accordingly. Not to mention the conversion is a pain in the butt.

I guess I would question why? 40 is already a very high pressure pistol round. I think I'd worry about the firearm turning into a grenade and earning the nickname Stumpy.

.40 has well-known limited case capacity for the size / weight bullets used. The reason I never used 180 gr. in .40 when I was loading it.

I would think so 10mm and 40 sw both use the same sizing die

They do.