What’s so great about 10 mm?

[Loyaljeeper]

The 10mm round is a good cartridge, but it's not the equivalent of the .41 mag. It's the equivalent of the .357 mag.

That’s not true. It’s no 41mag but it isn’t, in general, the equivalent of most 357 mag. For decades the standard 357 mag was a 158gr bullet at 1250fps in a 4” revolver. A 5” 10mm auto shooting a standard 180gr bullet is 1250 fps. A 4” 10mm revolver should be the same. That means you have a 10% heavier bullet, with 10% more cross sectional density, traveling the same 1250fps. This is not even a nuclear boutique load. Federal’s 10mm loads are neutered to 40s&w power levels. Remington, Sig, and Winchester get a little closer to the original Norma loads of 180gr@ 1200 plus. Speer’s new 10mm is a little weak with 200gr @ 1100. Boutique 10mm loads can reach close to 1400fps with 170-180 grain bullets.

I have shot more 10mm ammo than many of you guys have seen on shelves. My 3” 10mm revolver hits plates harder than my 3” 357 mags and it recoils more.

 

[uncleted327]

That’s not true. It’s no 41mag but it isn’t, in general, the equivalent of most 357 mag. For decades the standard 357 mag was a 158gr bullet at 1250fps in a 4” revolver. A 5” 10mm auto shooting a standard 180gr bullet is 1250 fps. A 4” 10mm revolver should be the same. That means you have a 10% heavier bullet, with 10% more cross sectional density, traveling the same 1250fps. This is not even a nuclear boutique load. Federal’s 10mm loads are neutered to 40s&w power levels. Remington, Sig, and Winchester get a little closer to the original Norma loads of 180gr@ 1200 plus. Speer’s new 10mm is a little weak with 200gr @ 1100. Boutique 10mm loads can reach close to 1400fps with 170-180 grain bullets.

I have shot more 10mm ammo than many of you guys have seen on shelves. My 3” 10mm revolver hits plates harder than my 3” 357 mags and it recoils more.

It is absolutely true. At it's best the 10mm is the equivalent of a good 357 Magnum. Underwood makes the hottest ammo I've found in either caliber and they have both 180 and 125 grain 357 loads that deliver more energy than any of their 10mm options in any weight. If you find a 10mm load that can outdo their stated 125 grain 1700fps and 800 ftlbs then you can back up your claim. Until then its unsubstantiated opinion...

 

[Mike_Fontenot]

Send the cylinder out to Mark at Pinnacle Precision and you'll have a 10mm. Magnum the equivalent of the .41 Mag.
I did.

The 10mm Magnum, which Tex was referring to, is darn close.

I've never heard of 10mm magnum. Underwood doesn't list it. S&W's description of the 610 doesn't say anything about 10mm Magnum. But the above posters have apparently seen it. And I guess they've established that the 610 can handle it if the cylinder holes are elongated.

 

[Hub]

BUFFALO BORE HEAVY 357 MAG
180 gr. JHP (1,500fps/M.E. 899 ft. lbs.)

 

[Loyaljeeper]

I knew someone would quote the ft/lbs of energy, the most worthless numbers in ballistic studies. This Underwood is the hottest 10mm I will dare shoot. I will not buy anymore. It’s too much for a 40oz revolver and I was told to not shoot anymore steel plates with it at our LE range. At first they accused me using a rifle on them.

Find me a 357 mag load over 200grains that will produce more than 1200fps.

I normally don’t bother with any 10mm load under 180grains. There is no point. The guys that tuned me into 10mm handloading push 155 grain loads 1600 fps in full size Glocks. I just like the revolver because I get free 40 ammo and loads of it.

 

[Loyaljeeper]

My argument was meant to be strictly store bought loads by the big three and 10mm beats 357mag. Of course there are exceptions.

 

[sparkyvega]

Be still, my beating heart!

The upcoming P320/10 will very likely continue the revival of the 10mm

 

[BLUEDOT37]

I've never heard of 10mm magnum.
Underwood doesn't list it.
S&W's description of the 610 doesn't say anything about 10mm Magnum.
But the above posters have apparently seen it.
And I guess they've established that the 610 can handle it if the cylinder holes are elongated.

The 10mm Magnum runs at the same max pressure as the 10mm Auto, 37.5K psi. The 610's N-frame can handle it.

It's a wildcat cartridge as no one has had it SAAMI certified/standardized yet.

You have to ream the standard 10mm Auto M610 cylinder's chambers longer to accept the 10mm MAG, which can be done with a standard Dave Manson 10mm Auto reamer.

A Starline 10MAG case has ~5.9% less capacity than a Starline 41MAG case.

I load my 165gr & 180gr 10MAGs to approximately 41MAG 170gr load data.


TAFFIN TESTS: THE 10MM MAGNUM
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Taffin Test the 10 mm Magnum

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[jughed440]

I've never heard of 10mm magnum. Underwood doesn't list it. S&W's description of the 610 doesn't say anything about 10mm Magnum. But the above posters have apparently seen it. And I guess they've established that the 610 can handle it if the cylinder holes are elongated.

The N-Frame can handle .44 Magnum, 10mm Magnum will be no problem.
If all outside dimensions are the same, the 610 has thicker cylinder walls and barrel than the .44s.
My question for the knowledgeable ones...is the stainless alloy used to make the 10mms any different from the .44 Mag. models??

 

[Frank Black]

Originally Posted by Mike_Fontenot
The 10mm round is a good cartridge, but it's not the equivalent of the .41 mag. It's the equivalent of the .357 mag.

The 10mm Magnum, which Tex was referring to, is darn close.

Actually, the 10mm Magnum exceeds the ballistics of the .41 Magnum, per John Taffin. He thought the 10mm Mag was the better round due to its versatility.

The 10mm Magnum has definite applications as a hunting pistol and a long range silhouette pistol. Shooting informally at long ranges of 100 to 200 meters and using rocks as targets convinced me of this. Anything the .41 Magnum can do, the 10mm Magnum can also do and perhaps do it even a little faster and a little better. That is a tough confession for an old sixgun man to make. -- John Taffin

 

[Loyaljeeper]

There is reason to believe the metal from one steel model to the next will be the same provided both frames were manufactured around the same time.

 

[jughed440]

There is reason to believe the metal from one steel model to the next will be the same provided both frames were manufactured around the same time.

I would think so too, but knowing that S&W used different alloys for older .38 and .357 models i can never be sure.

 

[uncleted327]

Funny how ft-lbs of energy is only meaningless once it disproves someone's BS. The fact remains the 10mm doesn't beat the 357 Magnum unless you start adding in your yeah buts, what ifs and so forth. Of course you won't find a 200 grain 357 load because the 10mm can utilize heavier bullets, who cares. Cherry picking two loads to compare in order to try and prove your feelings correct about the 10mm doesn't make you right. It doesn't beat the 357 and was never close to the 41 Magnum. You people who want to worship the 10mm as some hammer of Thor are welcome to your own opinion, but not your own facts.

 

[Loyaljeeper]

Funny how ft-lbs of energy is only meaningless once it disproves someone's BS. The fact remains the 10mm doesn't beat the 357 Magnum unless you start adding in your yeah buts, what ifs and so forth. Of course you won't find a 200 grain 357 load because the 10mm can utilize heavier bullets, who cares. Cherry picking two loads to compare in order to try and prove your feelings correct about the 10mm doesn't make you right. It doesn't beat the 357 and was never close to the 41 Magnum. You people who want to worship the 10mm as some hammer of Thor are welcome to your own opinion, but not your own facts.

I didn’t cherry pick loads. Someone cherry picked a specific 357 load that I have never seen on shelves because it’s ridiculously pushed past what most 357 mags could handle and expensive. I own about seven 357 mags and one 10mm. I have no biased interest in 10mm.

If 10mm was as common as 357mag I’m sure we would have some ridiculous loading for it also. Until then, handloaders will rival that one load that you cite that represents less than 1% of 357 mag ammo sold.

I am only talking mass produced ammo by large manufacturers which for years has been a 158gr 357mag at 1250 vs a 180 10mm at the same velocity. A heavier bullet, with a larger diameter, at the same velocity or even slightly less is more powerful.

 

[Mike_Fontenot]

I've never heard of 10mm magnum. Underwood doesn't list it. [...]

I DID find some 10mm magnum listed on Doubletap's webpage. They didn't include any ballistic or dimensional info on it though.

 

[Mike_Fontenot]

The 10mm Magnum runs at the same max pressure as the 10mm Auto, 37.5K psi.

That surprises me. I had assumed that most of the extra performance was due to a higher max pressure. That must mean that the extra power comes from having room for a lot more powder in the case. (A better way to put that is that, if the max pressure is the same, the only way the bullet velocity or energy could be substantially higher is if the high pressure lasts for a longer time of bullet travel).

You have to ream the standard 10mm Auto M610 cylinder's chambers longer to accept the 10mm MAG, which can be done with a standard Dave Manson 10mm Auto reamer.

In your photos of the three cartridges, the 10mm magnum case looks a LOT longer that the 10mm case. I'm surprised there is enough extra length in an N Frame cylinder to accommodate that.

 

[Frank Black]

I DID find some 10mm magnum listed on Doubletap's webpage. They didn't include any ballistic or dimensional info on it though.

Don't know why. Not very long ago the fps/fpe stats could be found listed under each 10mm Mag load that DT offered. I think there were four such loads. They must've removed the ballistic stats when the ammo sold out.

Below are Taffin's chronographed readings from his handloads. (The link to his article on the 10mm Magnum is posted below the quoted material).

Note that his AMT semi-auto 10mm Mag pistol had a 8 3/8" barrel, but a good chunk of that measurement included the chamber. So it would be interesting to do a comparative range session with Ruger's 7" 10mm SRH, with its cylinder chambers suitable reamed to 10mm Mag specs, to fire the same loads and see if the same or closely similar velocities would result, other variables being equal.

Or failing that, maybe one of the many 6.5" S&W 610s whose cylinders wheelgun 'smiths like Hamilton Bowen converted to 10mm Mag specs.

JOHN TAFFIN TESTS: THE 10MM MAGNUM
LOADS FOR THE 10MM MAGNUM

FIREARM: AMT/IAI BARREL LENGTH: 8 3/8"

CHRONOGRAPH: OEHLER MODEL 35P TEMPERATURE: 59 DEGREES

BRASS: *-* 10MM MAGNUM PRIMER: FEDERAL 155

BULLET: HORNADY 180 XTP

LOAD MV GROUP CASE EXPANSION*

15.0 GR. AA#9 1203 1 3/4" .424"

16.0 GR. AA#9 1309 1 7/8" .424"

17.0 GR. AA#9 1430 4 1/4" .4245"

18.0 GR. AA#9 1505 1 3/8" .4245"

21.0 GR. H110 1611 2" ES=25 .4255"

21.0 GR. WW296 1625 1 1/2" ES=11 .4255"

17.0 GR. #2400 1464 1 3/8" .425"

18.0 GR. #2400 1550 2 3/4" ES=23 .425"

14.0 GR. BLUE DOT 1539 2 1/2" .425"

BULLET: HORNADY 200 FMJ

LOAD MV CASE EXPANSION*

15.0 GR. AA#9 1256 .4245"

16.0 GR. AA#9 1338 .4245"

17.0 GR. AA#9 1431 .4245"

20.0 GR. H110 1499 .424"

21.0 GR. H110 1599 .425"

20.0 GR. WW296 1499 .424"

21.0 GR. WW296 1622 .425"

22.0 GR. WW296 1678 .425"

16.0 GR. #2400 1386 .424"

17.0 GR. #2400 1474 .4245"

18.0 GR. #2400 1522 .4245"

12.0 GR. BLUE DOT 1382 .425"

13.0 GR. BLUE DOT 1443 .425"

14.0 GR. BLUE DOT 1532 .425"

MEDIOCRE ACCURACY WITH 200 GRAIN FMJ BULLET IN 10MM MAGNUM.

BULLET: HORNADY 200 XTP

LOAD MV GROUP CASE EXPANSION*

16.0 GR. AA#9 1379 1" .425"

17.0 GR. AA#9 1452 2" ES=20 .425"

18.0 GR. AA#9 1477 2 5/8" .4255"

20.0 GR. H110 1507 1" .4245"

21.0 GR. H110 1597 3 1/4" ES=26 .425"

20.0 GR. WW296 1561 3" .425"

21.0 GR. WW296 1621 2" .426"

16.0 GR. #2400 1421 3 1/8" .425"

17.0 GR. #2400 1503 2 1/4" ES=25 .4255"

18.0 GR. #2400 1569 5/8" .4255"

12.0 GR. BLUE DOT 1391 2 1/4" .425"

13.0 GR. BLUE DOT 1461 2 1/8" ES=28 .4255"

14.0 GR. BLUE DOT 1529 3" .426"

Taffin's full article on the 10mm Magnum and its background can be found here:

Taffin Test the 10 mm Magnum

 

[oldman10mm]

I'm surprised there is enough extra length in an N Frame cylinder to accommodate that.

The 10mm Magnum shows an overall cartridge length 1.555". The N-frame handles 357M-1.590", 41M-1.590", 44M-1.610", & 45LC-1.600". There's adequate length in the N-frame cylinder to accommodate it.

 

[Hub]

I didn’t cherry pick loads. Someone cherry picked a specific 357 load that I have never seen on shelves because it’s ridiculously pushed past what most 357 mags could handle and expensive.

"This ammo is safe to shoot in ANY all steel 357 revolver - this includes J-frames. This ammo is no harder on your gun than any other normal 357 ammo."

 

[Hub]

Boutique 10mm loads can reach close to 1400fps with 170-180 grain bullets.

You say I`m cherry picking when I show you a boutique load that surpasses your mighty 10mm. 180 is the standard weight for 10mm and heavy for the 357 magnum.