10mm Auto

[CandG]

My primary CCW is a G29, fed by a steady diet of Underwood 155gr XTP's, Xtreme Penetrators, and Xtreme Defenders

I'm thinking about making a complete switch to Xtreme Defenders for everything (home defense, bear defense, and everything in between), but I haven't done enough testing on it to completely make that decision yet.

In the meantime, I carry XTP's 99% of the time, and in the backcountry I carry magazines loaded with alternating XTP's and Xtreme Penetrators (the 2 cartridges pictured in my signature). Haven't had to use it thankfully, but I'd imagine that combo would put down just about anything I could ever encounter in CA.

[Bill Steele]

I have a question for the old school S&W 1006 guys.

Most of the newer 10mm's seem to require a barrel change to shoot .40 cal. I have been told you don't need to do anything to a 1006 to run 40 cal ammo thru it.

1. Is that true?

2. have you personally done it?

3. Anything I should know?

Most 10mm guns will cycle and shoot 40 successfully. The question of the "safety" of such an endeavor centers around the fact that the 40 case is shorter than the 10mm case. When you chamber a 40 in a 10mm chamber, the extractor holds the case near the breech face.

The "safety" question then is, if the case were to slip the extractor for some reason, will the gun fire? If a 40 case went past its 10mm extractor, the round will slide down and headspace off the case rim (like it normally does in a 40 chamber) but the head would be largely unsupported and as such likely will suffer a case head separation in the event the round was fired. Most experienced shooters view a case head separation form of kaboom as the least menacing as kaboom's go, as it usually just means some hot gases flying around up in you line of vision, possibly a minor singe of your skin on your hand(s) near the chamber, the mag getting ejected down and out of the gun, maybe some etching of the breech face or chamber, jarring for most, but nothing broken. If this kind of failure doesn't bother you, then any 10mm gun will likely work for your 40 ammo.

On the other hand, if a case head form of kaboom is not something you ever want to experience, a closer look at the 10mm gun you want to shoot 40 out of is in order.

1911's are probably the worst as the extractor is the weak link in its design (can get out of tune), in addition, the 1911 usually doesn't have a positive stop on the firing pin travel, so a 40 round that slips its extractor, will likely fire when the 1911 firing pin reaches down into the chamber and hits the primer of the slipped round.

Glocks are good to go for 40 in their 10mm chambers as they both have very stout and well designed extractor and the firing pin has a positive stop such that even in the extremely rare event of a broken extractor, the firing pin won't reach the primer, so nothing happens except a "click".

I can't speak for the S&W guns, but I suspect their firing pin is more like a 1911, in any case, it is easy to tell. Field strip the gun and push the firing pin forward. If it stops before it would reach the 40 case head if it slipped past the extractor, then you may want to think twice. On the other hand, external extractor guns tend to be pretty reliable in that area (Kimber's early effort notwithstanding), so again, how much risk you are actually taking is a matter of opinion, not fact.

I have shot tens of thousands of 40 cased ammo from my 10mm Glocks, never a hitch.

Probably TMI, it is just that an accurate answer won't fit on a bumper sticker.

[71MUSTY]

Most 10mm guns will cycle and shoot 40 successfully. The question of the "safety" of such an endeavor centers around the fact that the 40 case is shorter than the 10mm case. When you chamber a 40 in a 10mm chamber, the extractor holds the case near the breech face.

The "safety" question then is, if the case were to slip the extractor for some reason, will the gun fire? If a 40 case went past its 10mm extractor, the round will slide down and headspace off the case rim (like it normally does in a 40 chamber) but the head would be largely unsupported and as such likely will suffer a case head separation in the event the round was fired. Most experienced shooters view a case head separation form of kaboom as the least menacing as kaboom's go, as it usually just means some hot gases flying around up in you line of vision, possibly a minor singe of your skin on your hand(s) near the chamber, the mag getting ejected down and out of the gun, maybe some etching of the breech face or chamber, jarring for most, but nothing broken. If this kind of failure doesn't bother you, then any 10mm gun will likely work for your 40 ammo.

On the other hand, if a case head form of kaboom is not something you ever want to experience, a closer look at the 10mm gun you want to shoot 40 out of is in order.

1911's are probably the worst as the extractor is the weak link in its design (can get out of tune), in addition, the 1911 usually doesn't have a positive stop on the firing pin travel, so a 40 round that slips its extractor, will likely fire when the 1911 firing pin reaches down into the chamber and hits the primer of the slipped round.

Glocks are good to go for 40 in their 10mm chambers as they both have very stout and well designed extractor and the firing pin has a positive stop such that even in the extremely rare event of a broken extractor, the firing pin won't reach the primer, so nothing happens except a "click".

I can't speak for the S&W guns, but I suspect their firing pin is more like a 1911, in any case, it is easy to tell. Field strip the gun and push the firing pin forward. If it stops before it would reach the 40 case head if it slipped past the extractor, then you may want to think twice. On the other hand, external extractor guns tend to be pretty reliable in that area (Kimber's early effort notwithstanding), so again, how much risk you are actually taking is a matter of opinion, not fact.

I have shot tens of thousands of 40 cased ammo from my 10mm Glocks, never a hitch.

Probably TMI, it is just that an accurate answer won't fit on a bumper sticker.

No that was good. perhaps more technical then I asked for, but way better then a "I do it, go for it" Gives me some food for thought and more insight into the question.


Shooting .40 thru is not something I would do on a regular basis, but it is good to know in a SHTF situation. I do have a spare barrel but that doesn't really add much to the question.

[igorts]

add me to 10mm funs.
G29SF
G20SF with long slide and RDS.
Kimber Eclipse 10mm
looking for S&W 610 and 310

[rubbman]

While I have no interest in the .40, the 10mm continues to call my name...

But then again, I still want a .38 super as well...

This place is bad for your budget.

WORD! I want a 10mm.

[johnwin84]

I love the 10mm. I have a p220, eaa witness hunter and a dan wesson silverback.

[LoadedM333]

Here's the result of a scientific study of caliber comparisons I found on the net. Tells the whole story

Good one!

[Vorais]

Glock 20Sf (need to improve the trigger, it sucks )
Kimber Custom Eclipse II in 10mm
20k+ rounds of various underwood ammo in 10mm.

Energy is similar to hot .357 Mag, or about double that of the .45acp (~800ft-lbs)

I love the 10mm. But I guess I like the bigger calibers or very fast bullets. A couple of my other favorite pistols of similar power are my DE mk1 and a Magnum research BFR in 45-70...

[Cali74]

I love my G20sf.
Then I tried it with Underwood ammo and I loved the 10mm even more.
Can't wait to start reloading for it.
The best was letting my little mom shoot my G20sf at the gun range and telling her to "Hold on tight".
She went through the mag in short order and was smiling when done.
Then again she has no problem shooting her 357 mag revolver

[G38xOC]

Glock 20Sf (need to improve the trigger, it sucks )
Kimber Custom Eclipse II in 10mm
20k+ rounds of various underwood ammo in 10mm.

Energy is similar to hot .357 Mag, or about double that of the .45acp (~800ft-lbs)

I love the 10mm. But I guess I like the bigger calibers or very fast bullets. A couple of my other favorite pistols of similar power are my DE mk1 and a Magnum research BFR in 45-70...

you stocked up 20k + worth of underwood stuff ?

[Vorais]

you stocked up 20k + worth of underwood stuff ?

Yes, and I want a lot more. I'm stocking up on all ammo right now. Honestly I'm surprised more people aren't with the Newscom stuff and the how politicians in general are pushing toward more gun control laws.

Hopefully when I move everything later across the bay my boat holds up...

[CandG]

Glock 20Sf (need to improve the trigger, it sucks )
Kimber Custom Eclipse II in 10mm
20k+ rounds of various underwood ammo in 10mm.

Energy is similar to hot .357 Mag, or about double that of the .45acp (~800ft-lbs)

I love the 10mm. But I guess I like the bigger calibers or very fast bullets. A couple of my other favorite pistols of similar power are my DE mk1 and a Magnum research BFR in 45-70...

So you're the reason why they're always out of stock when I go to order 10mm from them

And that's insane by the way... $20k+ in underwood 10mm?? I mean, I'm all for ammo hoarding, but do you need that much defensive ammo? For myself, I'm good with a couple thousand defensive rounds in various calibers, and the rest of it just cheap target loads. I don't see myself needing to use 20k rounds for self defense, if I do I need to move or stop making people angry at me or something... lol. But if you've got infinite ammo budget, then I guess sure why not.

[Mike-4]

Love my 10mm girls:

Prom queen (S&W 1006)


Hoochie momma (G20SF)

[JTROKS]

20k 10mm rounds?

I wonder how many 5.56, 7.62x39 & 7.62x51 ammo you have?...

[glock_nor_cal]

20k+ rounds of various underwood ammo in 10mm.

Pics or it didn't happen