10mm or 40

Here are, in my view, the questions that you need to answer in order to answer your ultimate question:

1. Do you reload? If you reload, the 10mm can be made into a wide variety of things. If you don't the ammo costs will likely keep you from shooting it very much.
2. Do you want to run the cartridge in a particular platform? If so, was that platform designed for a .45ACP-length round or a 9mm/.40 round. In the former, such as a 1911 or a large-frame Tanfoglio, the 10mm will likely be more reliable (or easier to make reliable). In a gun like the Glock that gets sized up and down, it won't matter.
3. Which theory of terminal ballistics do you favor? Are you a bullets-just-poke-holes Facklerite? Or a hydrostatic-shock/speed-kills person? If you're in the former, see question #4. If the latter, you can run a 10mm up 100-150fps faster. It's got a slightly higher SAAMI pressure rating, and a bigger case. Those two combine to make for more power on tap, if that's what you want.*
4. What do you think you might need to shoot? If you need to poke deeper holes, such as ensuring penetration on a large animal with tough bones, then the ability of a 10mm to handle things like 200gr hard-cast bullets might make a difference.

For most shooters, the answers will lead towards a .40. For some, the answers will point towards a 10. I have a 10mm and love it, FWIW.


* I note that some people who don't care about SAAMI specs have reported that they can match or exceed 10mm loads using .40 brass loaded to 10mm length. That, of course, require a gun big enough to cycle those longer loads, and a barrel with a long enough lede/throat to accept the long bullets. For most people, this is all moot.

Plus, if you pit a "real" 10mm against a "real" .40 (often overlooked), there's not that much difference.

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Yeah, it's only a 40% increase in KE. Of course, some might consider that significant...........

So if i take a G20 in the woods with, say a 180gr XTP running 1300 fps I'm golden but if I take a G35 with a 180gr XTP running 1250 fps I'm not?

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The real world difference with max loads is more like 1,150 FPS vs 1,350 FPS.

I do find it amusing that guys who will poo-poo the .380 and extoll the virtues of 9x19mm are the same ones who don't see the benefit of a 10mm over a .40....

Anyway, I've pushed both cartridges pretty dang hard in 3rd gen S&W guns, I know what the upper limits are. What most people don't realize is a case that is only 16% longer, when it is a pistol cartridge, has much more than a 16% increased powder capacity.

In terms of grs. H2O, the 10 has 28% increased capacity. But that still doesn't tell the whole story. It's only once you figure the capacity with bullet seated that you have an accurate figure.

With a 180 gr. bullet, the 10mm has almost 50% more powder capacity than the .40 S&W, and that translates into top loads producing 30-40% greater energy. Energy in and of itself means nothing, but it gives us a base line from which to compare similar cartridges. Energy indicates the ability to do work; where bullets are concerned, higher energy means driving heavier bullets at higher velocities, which in turn means potential to produce deeper and possibly larger diameter wounds.

10mm or 40 ?

10mm hardball is what I want when confronted by perps wearing body armor or a charging Grizzly.

As for recoil, 10mm coming out of a full-size 52 oz 1911, is mild, about 9mm level. A heavy handgun yes, but being a 1911, easily conceal carried, 1911 folks will understand. I carry mine if going into a hi-risk area.


PS RE: Arizona vs Fish, post #22

The biggest problem was that the victim was unarmed yet shot 3 times in the chest with a 10mm 1911 handgun. Shooting unarmed victims who are out walking (their two dogs) is a huge no-no.

Depends upon what you plan to do with it and the form factor you want.

Any DA or double column gun in 10mm is going to be unusably large in the grip, with too much trigger reach for me. Even a Glock 20 is too big.

An M1911 in 10mm will fit most hands.

I've got a Glock 22, and find the recoil uncomfortably sharp. Not painful, just too violent to easily maintain control in rapid fire. If I ever get another .40 S&W handgun, it'll have a steel frame.

For carrying the chambering makes no difference. Buy the one you can shoot best.
Mind you, you'll likely find the 10mm isn't easy to come by, everywhere. It's not any better than a .45 in the bush. And a .45 is next to useless.
A 10mm will just annoy a charging bear of any kind. Not that you'd have time to recognise Yogi is coming for you, draw and accurately place a shot before he's on you. Inside 100 yards, he'll be on you in less than 6 seconds.

MachIVshooter said:

The real world difference with max loads is more like 1,150 FPS vs 1,350 FPS.

I do find it amusing that guys who will poo-poo the .380 and extoll the virtues of 9x19mm are the same ones who don't see the benefit of a 10mm over a .40....

Anyway, I've pushed both cartridges pretty dang hard in 3rd gen S&W guns, I know what the upper limits are. What most people don't realize is a case that is only 16% longer, when it is a pistol cartridge, has much more than a 16% increased powder capacity.

In terms of grs. H2O, the 10 has 28% increased capacity. But that still doesn't tell the whole story. It's only once you figure the capacity with bullet seated that you have an accurate figure.

With a 180 gr. bullet, the 10mm has almost 50% more powder capacity than the .40 S&W, and that translates into top loads producing 30-40% greater energy. Energy in and of itself means nothing, but it gives us a base line from which to compare similar cartridges. Energy indicates the ability to do work; where bullets are concerned, higher energy means driving heavier bullets at higher velocities, which in turn means potential to produce deeper and possibly larger diameter wound

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Okay lets look at what you've said here. You claim the real world difference is 1150 vs 1350. Okay let me be clear to say that with a G20 and a KKM barrel I've loaded 180's to 1350 fps, so that part is true. But also I've ran 180gr .40's to 1200 fps in a 4" G23, both charges btw require more than book max charges of powder. From a stock G35 I've ran 180gr hardcasts to 1300 fps and 180gr jacketed to over 1270. So where do you get 1150 fps? I don't deny that a 180gr @ 1270 from a G35 isn't on the spicy side, it is but at the same time, it's no spicier than having to exceed book max to wring 1350 fps out of the G20.


Again, if I go out into the woods with a Glock 20 shooting 180gr XTP's (or whichever JHP you prefer) at 1350 and a G35 shooting the same exact bullet at 1270, what real absolute advantage does the 10mm offer?? None, no animal will ever know the difference. So does ~70 fps equal 30-40% more energy? Not a chance. Take a smaller platform, if a G29 was pushing the same bullet to 1275 and a G23 to 1200, who in their right mind would ever say that the slightly faster 10mm will absolutely kill whereas the slightly slower .40 absolutely won't? That rather small velocity difference will never be missed, but you'll burn more powder for nothing with the 10mm.

Your powder capacity figures are a bit off the mark too. Lets use Longshot powder for instance, if I allow up to .5gr over book max I come up with 10.0gr for the 10mm (9.5gr book max) and 8.5gr for the .40 S&W (8.0gr book max), that's nowhere near 50% more capacity, simple math proves that.

I like the Glock 20 as a woods gun (that's what I carry, with Buffalo Bore 220 gr hardcasts), but outside of animal defense I don't know that I'd pick it over 40S&W. Here in Alaska, ammo availability for 10mm Auto is extremely limited compared to 40S&W (being divided from mainland America by Canada, we can't mail order ammo), which is the biggest sticking point I have with the idea of the caliber for general self-defense.

I own and like my G-20, but for most people 40 makes more sense. As others have said the 10mm comes into its own loaded hot with heavy bullets for possible large predator defense. I use Double Tap 200 gr hardcast chronographed at 1300 fps. That is a small step below a 44 magnum fired from a 3-4" barrel. While I do like the 10mm, the only time I use it is in bear country. But for me, that is often enough to justify owning the gun and buying the expensive ammo.

For human threats the 40 is more than adequate, a lot cheaper to own and shoot. There are 180 gr 40 loads approaching 1100 fps, which isn't bad at all.

Mind you, you'll likely find the 10mm isn't easy to come by, everywhere. It's not any better than a .45 in the bush. And a .45 is next to useless.
A 10mm will just annoy a charging bear of any kind. Not that you'd have time to recognise Yogi is coming for you, draw and accurately place a shot before he's on you. Inside 100 yards, he'll be on you in less than 6 seconds.

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The only accurate part of this post is the part about ammo being hard to come by. It is, but worth the effort if you are in bear country. 200 gr hardcast 10mm bullets will out-penetrate 45 by a wide margin. No handgun is ideal, but there have been many attacks stopped by 357 magnum revolvers. They didn't just annoy the bear. The best 10mm loads will beat 357 mag by a small margin and 40 S&W will just about equal 357 mag. If 357 is acceptable as a minimum, either 40 or 10mm should be too.

Re: SDGlock23's post.

In principle you are right. Hot loaded 40's do come fairly close to 10mm. The difference to me is that I just don't feel comfortable with 40's shooting 180's faster than about 1150 fps. The 10mm can shoot 200's between 1200 and 1300 and not be pushing the envelope quite as much. I'm getting 1300 fps with 200 gr Double Tap factory loads in my G-20. They show the same 200 gr bullet @ only 1100 fps in 40 S&W. Those are the hottest loads (factory or hand load), that I'm aware of. I might not pick the 10 over 40 for only 70 fps, but will for 200 fps.

Get whatever you can fire most effectively.

10mm, IMHO, is for Experienced Pistoleers only.

In a CC package (G29-sf), the recoil is a bit much for tiny/average sized folks.
If you ain't a regular weightlifter & of large size, might be smarter to go with the .40

Noting that this is off a one-post wonder, I'll stop there.

G20 with a 40 barrel.

Okay lets look at what you've said here. You claim the real world difference is 1150 vs 1350. Okay let me be clear to say that with a G20 and a KKM barrel I've loaded 180's to 1350 fps, so that part is true. But also I've ran 180gr .40's to 1200 fps in a 4" G23, both charges btw require more than book max charges of powder. From a stock G35 I've ran 180gr hardcasts to 1300 fps and 180gr jacketed to over 1270. So where do you get 1150 fps? I don't deny that a 180gr @ 1270 from a G35 isn't on the spicy side, it is but at the same time, it's no spicier than having to exceed book max to wring 1350 fps out of the G20.

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Lots of conjecture here. Unless you have a strain gauge, you have no idea how much "spicier" one load is than the next from a pressure stand point. With proper power selection, 1,350-1,400 FPS from a 5" 10mm is well within the 37,500 SAAMI spec. Conversely, there is not a powder on the planet that gets a 180 gr. out of a 4" .40 at 1,270 FPS within SAAMI max pressures.

Your powder capacity figures are a bit off the mark too. Lets use Longshot powder for instance, if I allow up to .5gr over book max I come up with 10.0gr for the 10mm (9.5gr book max) and 8.5gr for the .40 S&W (8.0gr book max), that's nowhere near 50% more capacity, simple math proves that.

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No, they're not. From case mouth to web, the .40 is .687"; the 10mm is .807". A 180 gr. JHP will encroach ~.360" when seated to max OAL, leaving ~ .450" powder column in the 10mm and .330" in the .40 S&W; that's a 36% increase from .40 to 10mm. Now move into a 0.050" longer 200 gr. pill, that encroachment will equate a 42-44% difference. Get into the 220 or 230 cast bullets, you're beyond the 50% figure.

The difference is actually even a bit larger than this due to the case taper into the web, but for simplicity's sake, we're assuming a perfect cylinder for this exercise. A perfect cylinder with a length of .807" has 17% greater volume than a .687" cylinder of the same diameter, but the actual H2O case capacities reflect a 27-28% difference in these partially tapered cylinders with a more-or-less torispherical end. If you calculate the internal case taper, you would add about 10-11%, giving you a 46-47% case capacity increase with 180 grain bullets in a 10mm vs a .40 S&W.

So yes, it is simple math. You just don't seem to understand it.

Thomas article; bullet design....

Thomas stated the 10mm bullet profile would lead to jams & not properly seat. He also said the full power 10mm would cause excessive wear & tear, more than the 9x19mm or .40S&W.

10mm or 40. as far as power the 40 cal started its life being called the 10mm short. because it is basically a downloaded 10mm. to be frank the FBI scientist came up with the best personal defense round (in the late 80"s) which was the 10mm. But the FBI found out most of there agents couldn't shoot it well enough to qualify. So the 40 was invented( just a downloaded version of the 10mm). what i don't understand is there are a lot of guys out there that carry a j frame 357 with 357 ammo in it but say they practice with 38 because it doesn't hurt to shoot.

The 10 mm can be a handful with full house rounds but most manufactures don't produce rounds loaded to full 10mm spec. Now that i have said that, if you had to pick one i would say go for the 40, more options in firearms, ammo, holsters and still a good round for personal defense. But when i go into the woods i have to admit that i normally grab my G20 over one of my 44's. I will carry my G29 when i can conceal it but it is a brick of a gun but i can shoot it better than i can my S&W 640 PD.

The 10mm is substantially more powerful while 40 S&Ws are usually build on 9mm size platforms making them smaller and easier to carry. Anything from 9mm, to 40, to 45 Auto are functionally the same in effectiveness for self defense so go with what you like. I would not feel under gunned with any of them.

(Snip) RE: Arizona vs Fish, post #22

The biggest problem was that the victim was unarmed yet shot 3 times in the chest...

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Yeah, that was the crux of the issue!

To answer this in the simplest terms, the .40 is to the 10mm what the 38 special is to the 357 magnum.

Largely depending on your ultimate goal, you won't go wrong with either. I own three 10mm guns and five in 40 S&W. I like them all and they each perform as expected.

That being said, 10mm guns are usually rather heavy and even for a big guy like me I seldom carry one for human-based self defense. I do carry my Glock 27 on occasion.

Being a long term hand loader, and having accumulated a small mountain of 10mm brass, I shoot mine quite often. But given the relative scarcity of commercial 10mm ammunition compared to the other popular calibers, if I didn't roll my own my 10mm shooting would be severely curtailed. But, that's true of all my center fire guns.

And then there's the standard question, "Have you shot one?" They are a little different from other popular semi autos in the recoil department. However, if you're used to heavy caliber magnum revolvers it's no big deal.

RustyShackelford said:

Thomas stated the 10mm bullet profile would lead to jams & not properly seat.

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Then he's an ignoramus. What is "the 10mm bullet profile"? There are many different bullet profiles available. And it will use all the same ones that a .40 will use.

Find a better source. You're being taught total nonsense.

ATLDave said:

Then he's an ignoramus. What is "the 10mm bullet profile"? There are many different bullet profiles available. And it will use all the same ones that a .40 will use.

Find a better source. You're being taught total nonsense.

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Exactly. Since 1991 I've loaded thousands of rounds of 10mm using jacketed, plated and hard cast Truncated Cone bullets. I can't speak to everybody's experience, but I don't even remember the last time I had a feeding issue with those bullets. My experience on my guns (a pair of Glock model 20s and a S&W 1006) is that the 10mm is a fairly forgiving round when it comes to cartridge OAL.

I did have problems with the Lee 175 grain semi wadcutter bullet (TL401-175-SWC) feeding properly but that particular bullet didn't work well in any of my 40 cal guns either. Bad bullet design; not bad gun performance.

As mentioned pistol cartridges are really similar unless you get into Magnum territory, even then it's hit and miss unless you hit a vital organ. I prefer to have more rounds, thus the 9mm, or the 45 for HD. I can carry a 9 much easier than a hi cap 45 all day
Ideally a 357 with a 3 inch or 4 inch barrel is the way to go, but it's big heavy and has only 5-7 rounds. Considering the amount of rounds that may actually hit a moving target that may be shooting back at you, it may be smarter to have a gun that can lay down some cover fire if needed.
Sometimes it's better to be able to get out of there, especially if there are more than 1 bad guys.

10MM vs 40 S&W for carry? I choose to carry the 40 S&W because I can shoot it more efficiently for CCW self defense. I love the 10MM and shoot it often. I see many people question the difference in velocity between similar bullet weights and here is what I have from two reloading manual sources. Richard Lee 2nd Edition, 40 S&W 180 jacketed bullet, 1,142 fps max velocity with vN350. Richard Lee 2nd Edition, 10 MM, 180 jacketed bullet, 1,290 fps max velocity with Accurate#9. That is an increase of 148 fps in velocity to the 10MM. Then the Hornady 7th Edition max's out the 40 S&W, 180 grain at 1050 verses the 10MM, 180 grain at 1,250 fps. That is a 250 fps increase to the 10MM.

In handgun comparisions, 150 to 200 fps increase is a substantial difference. Shooting different stuff like wood boards, concrete block, etc you do see a difference in penetration and bullet expansion between the two rounds. The 10MM power is very nice in a semi-auto handgun.

zeke4351 said:

View attachment 203101View attachment 203102

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I've got these two graphics too. The penetration comparison "mushroom cloud" is largely wishful thinking; the chart is real and quite possible with the right powder. But, the marginal gain you get from going into the nuclear range for 10mm is just that ... marginal, and not worth it. Nuclear level loadings are more expensive, hard on the most robust gun and brass is rather short lived.

If I require the nuclear level of power, I'll go to one of my .44 Magnums or my .454 Casull. And if I need still more power I go to a rifle. And since I just added Streamlight TLR-2s to my AR type guns they can do quite well as a home defense piece. And in my neck of the woods, 30 round magazines are the norm. Stoked with the proper ammunition, that's my idea of "nuclear" level protection.

In the backwoods? 10mm 180 grain FMJ or TC cast at about 1,150 fps. If more is needed, magnum or rifle as stated above.

Jorzac said:

To answer this in the simplest terms, the .40 is to the 10mm what the 38 special is to the 357 magnum.

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Except that the .40 is closer to the .357mag and the 10mm closer to the .41mag in energy levels.

I've looked at 10mm guns so many times, but I can't justify them as I don't reload.

I did pick up a .40 during the last ammo drought. Great shooter and it was nice to be able to feed it when 9mm/.38 special/.45 were nowhere to be found.

I will probably pick up a 10mm down the road, but for day to day between the .40 and 10mm, I'm just fine with the .40.