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

[The Heretic]

It just occurred to me that this might be possible.

However the case dimensions are slightly different

10mm Auto:



.40 S&W


Which surprised me a bit. Will an appropriately shortened 10mm Auto case fit into a .40 S&W chamber?

I am given to understand that the 10mm case has a stronger web, and shortened it would have less case capacity than a .40 S&W case.

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[Benchrest]

One way to find out, I suppose.

 

[The Heretic]

One way to find out, I suppose.

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.

 

[Nosferatu]

You'd have to be careful with powder selection and bullet seating. The S&W uses small primers vs large primers on the 10mm.

I don't doubt it could work, but the age-old @arakboss adage applies: Why all the trouble?

 

[arakboss]

It should work. I had many more large pistol primers than small when I was previously looking into it. After a few purchases of small pistol primers from Normausa and a major score from a private seller, I have way more small pistol primers than large pistol primers. My supply of large pistol primers will now be reserved for shotgun hulls, 10mm, various 44 loads, 45 colt, and reduced large rifle loads.

 

[The Heretic]

You'd have to be careful with powder selection and bullet seating. The S&W uses small primers vs large primers on the 10mm.

Agreed.

I don't doubt it could work, but the age-old @arakboss adage applies: Why all the trouble?

Power! Give me more power!

 

[25-06]

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.

I've read that 40 brass is inherently stronger than 10mm.

 

[The Heretic]

I've read that 40 brass is inherently stronger than 10mm.

Per Wikipedia the web is thicker/stronger in the 10mm because when they were designing the .40 they opened up the internal dimensions to get more capacity and less pressure?

During this collaboration with the FBI, S&W realized that downsizing the 10 mm full power to meet the FBI's medium velocity specification meant less powder and more airspace in the case. They found that by removing the airspace they could shorten the 10 mm case enough to fit within their medium-frame 9 mm handguns and load it with a 180 gr (11.7 g) JHP bullet to produce ballistic performance identical to the FBI's reduced-velocity 10 mm cartridge. S&W then teamed with Winchester to produce a new cartridge, the .40 S&W. It uses a small pistol primer whereas the 10 mm cartridge uses a large pistol primer.

.40 S&W - Wikipedia

en.wikipedia.org

 

[25-06]

Per Wikipedia the web is thicker/stronger in the 10mm because when they were designing the .40 they opened up the internal dimensions to get more capacity and less pressure?

.40 S&W - Wikipedia

en.wikipedia.org

It was on the 1911 forum. Someone surmised that the 40 has the smaller primer pocket compared to the 10 so somehow making it stronger.
I'm dubious myself. I don't own a 10 yet, and have a 4006 that is gathering dust in the safe.

 

[The Heretic]

It was on the 1911 forum. Someone surmised that the 40 has the smaller primer pocket compared to the 10 so somehow making it stronger.
I'm dubious myself. I don't own a 10 yet, and have a 4006 that is gathering dust in the safe.

Yup - I've seen people assert the .40 is stronger brass, but that kind of goes against trends and from what I have read of "official" sources, the facts.

 

[25-06]

Yup - I've seen people assert the .40 is stronger brass, but that kind of goes against trends and from what I have read of "official" sources, the facts.

The bigger question I guess is: is 10 brass scarce or expensive compared to 40?
My son bought a Rapide in 10 and I'm looking to get my own (not a Rapide, I'm too Fuddy) and if I do it's high volume reloading in my progressive.

 

[NeoBlackdog]

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.

 

[kopcicle]

Power! Give me more power!

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)

 

[Benchrest]

Then, by all means

http://10mm-reloaded.com/random/10mm-MAG_cut_down_to_10mm.html

 

[Certaindeaf]

It just occurred to me that this might be possible.

However the case dimensions are slightly different

10mm Auto:

View attachment 1874052

.40 S&W

View attachment 1874053
Which surprised me a bit. Will an appropriately shortened 10mm Auto case fit into a .40 S&W chamber?

I am given to understand that the 10mm case has a stronger web, and shortened it would have less case capacity than a .40 S&W case.

What loads were you shooting that indicated you had reached the/a performance wall using .40 cases? For some their wall is one load and the brass is toast (the primers fall out) like many long range service rifle competitors do.. or any sort of high-stakes motor race.
For me it'd be 3 reloads with the third having noticably looser pockets but not actual trash yet.

 

[oremike]

How about I trade you 2 40 S&W for 1 10mm?

 

[Benchrest]

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.

Huge proponent of safety but let's not be overly dramatic, that's what Spectra gloves are for

I jest

 

[Twodogs]

I loaded some very hot .40's with a 180gr bullets and longshot powder.
They shot great out of the Glocks.but way to hot for every day stuff.

 

[JO JO]

Will an appropriately shortened 10mm Auto case fit into a .40 S&W chamber?

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

 

[oremike]

On doing some quick research a shortened 10 mm will fit in a 40 chamber. I've shot 40 in a 10. Now some pressure numbers 40 S&W guns and cases are made to withstand 35,000 PSI. A 10mm case and gun is made too withstand 38,000 psi. My thought is a 10% over pressure load in any gun any time is a bad idea. For me I shoot 40 in a 40 and 10 in a 10. Looking at the size and weight deference in the same brand (Sig) I shoot 40 in a P-229 and 10mm in a P-220. With out putting them both on a scale I can say the P-220 is bigger and heavier and 10 % would be a good guess. You want 10mm power, get a 10mm. Honestly it'll be worth it, you'll be able to shoot bigger bullets faster than you ever could with the 40 Short and Weak