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Old October 7, 2012, 04:41 PM   #1
papadork
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Kahr .9mm vs Kahr .40mm

I'm sticking with Kahr but I can't decide on the CM9 or the CM40. I heard that the CM40 doesn't have much muzzle flip like other 40's. Does anyone have an opinion on the CM40? They are both about the same size. I'm thinking what the heck, go for the bigger bang.
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Old October 7, 2012, 04:45 PM   #2
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I've had both. I now only have a PM9.
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Old October 7, 2012, 04:45 PM   #3
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I always prefer a 9mm over a .40. With modern hollowpoints, the effectiveness of the .40 has proven to be only slightly better than the 9mm; what matters far more is shot placement. And the slight increase in power doesn't make up for the lower capacity and slower follow-up shots. Add in the fact that 9mm ammo is considerably cheaper than .40, and it's no contest between the two. But that's just my opinion, the .40 is a good round that serves many people just fine.
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Old October 7, 2012, 05:07 PM   #4
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According to ballistics101.com, the 40 seems to have a lot more energy. Both specs listed below are Speer middle-of-the-road ammo.

Caliber Type W E MV
40 SW GDHP 165 484 1150
9mm GDHP 124 364 1150
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Old October 7, 2012, 05:20 PM   #5
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Energy doesn't always translate directly to real-world effectiveness. Current thinking among many experts is that the differences between the effectness of the 9mm vs .40 vs .45 is less than previously thought, especially when using quality modern hollowpoints. For example, Massad Ayoob used to be seen carrying a 1911 more than anything else; now he's more likely to be carrying a 9mm.
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Old October 7, 2012, 05:23 PM   #6
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Hello papadork and welcome to the asylum...

The Kahr brand is a good choice for a CC handgun. If you've not shot the 9mm and .40 Auto side by side in otherwise identical guns... I suggest you do so.

Like Theohazard and goodshot... I personally do not like the .40 Auto cartridge. Entirely subjective on my part, but I do not like the recoil impulse or shot to shot times of the .40 Auto when compared to other calibers. It's not a matter of recoil, as I own and shoot 10mm Auto regularly, it's simply that I don't find the trade-offs to be worth it as compared to a 9mm.

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Old October 7, 2012, 08:25 PM   #7
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...40mm?

Kahr 40mm? I didn't realize they were making grenade launchers or autocannons.

In all seriousness though, 9mm and 40mm come in pretty even in terms of performance on people. Go 9mm - more ammunition in any given magazine size, less cost, less muzzle flip. Etc. In other words, marginally superior but superior none the less.
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Old October 7, 2012, 10:26 PM   #8
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The depth is about the same, but the wound channels are a lot bigger with the 40.
I think the 40 is as good or better than the 45acp, especially if capacity is figured in.
9's arent on my radar unless its small.

Still don’t think I'd want a PM40 tho... the PM9 is a very nice shooting tiny 9mm, I think the same gun in a 40 would be rough to practice with.

I staunchly believe that 40 is the better round, but its limit is something like a Glock 27... no smaller than that for me thanks, and I'll take the G27 over the G26.
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Old October 7, 2012, 10:38 PM   #9
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If I only had one shot I'd prefer a .40 over a 9mm. But muzzle energy and wound channels in ballistic gel aside, the .40 has shown to have only a slight advantage over the 9mm in real-world shootings; an advantage that, in my opinion, doesn't make up for the disadvantages.
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Old October 7, 2012, 10:45 PM   #10
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I carry a Kahr PM40 routinely.

I don't particularly find it difficult or uncomfortable to fire, or to achieve reasonably rapid hits with.

In terms of capacity, its all relative.

If I can't resolve a sudden social dispute with 6 or 7 rounds of .40 S&W, it isn't clear to me how 7 or 8 rounds of 9mm is going to give me a significantly better chance. Given a spare magazine and the ability to reload with it, capacity seems to be one of those criteria that borders on irrelevant.

In terms of effectiveness, in all honesty I suspect that 2 or 3 solid hits with either 9mm or .40 S&W is going to remind an attacker that there is somewhere else he urgently needs to be. I'm unsure that its going to make a lot of difference - that said, in terms of ballistic energy there is measurably more energy with the .40; and assuming both projectiles expand, the .40 expands to a marginally greater diameter.

I suspect that if a shooter routinely works out with whichever caliber s/he prefers, that shooter is going to do as well with either caliber as the circumstances allow if they ever find themselves in a gunfight.

Just MHO. YMMV.
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Old October 7, 2012, 11:28 PM   #11
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Doc, you pretty much nailed it right there.

The two rounds are similar enough that it often just comes down to personal preference and which one you shoot better. Some people prefer the .40; me, I prefer the 9mm.

Though, if you're on the fence about which one to get, you might want to consider the cost of ammo. If you're like me and you don't have much extra money, you like to shoot a lot, you live in a tiny apartment where the wife won't allow any reloading equipment, then the 9mm comes out on top due to the significantly cheaper cost of ammo.
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Old October 8, 2012, 08:45 AM   #12
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I think the 40 will hit noticably harder during the first shot - its hard to quantify, but all other things being equal my theory is that the impact of the first 40 may buy me more time for the second shot, nullifying the follow-up advantage of the 9mm.

LIke the OP, I'd like to know from PM40 owners how well it shoots (by comparison to say, a PM9 or G27, etc)
I shot a PM40 long long time ago, and only recall it having noticably more recoil than my PM9, but to what degree is fuzzy memory.
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Old October 8, 2012, 10:47 AM   #13
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My choice is 9mm (I own a CM9). I think 9mm, for many reasons, makes more sense for this type of pistol, unless you just have to have .40S&W for commonality with a duty pistol.

The 9mm Kahrs also have a track record of being more reliable than other calibers. My CM9 has been 100% reliable in the nine months I've owned it.
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Old October 8, 2012, 03:14 PM   #14
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Quote:
The depth is about the same, but the wound channels are a lot bigger with the 40.
I think the 40 is as good or better than the 45acp, especially if capacity is figured in.
9's arent on my radar unless its small.
Good to see the same misconceptions coming back time and again from the same people.
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Old October 8, 2012, 04:34 PM   #15
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No.. the real misconception is that 9mm is really comparable to 40.
45acp and 40S&W are much more similar in their performance.

But thanks for the snarky clownish insult anyway...
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Old October 8, 2012, 04:38 PM   #16
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No.. the real misconception is that 9mm is really comparable to 40.
45acp and 40S&W are much more similar in their performance.
They're all equally mediocre in their performance on target, with highly marginal differences in terms of terminal effect. Thinking otherwise betrays your status as a ballistic layperson. I've seen you post long arguments on this forum that eventually drive you to admit you base your opinion not on empiricism but just "how you feel about it".

If we were talking about hunting, .45 ACP has some pretty clear advantages. We are not however discussing that.
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Old October 8, 2012, 04:49 PM   #17
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Just look at this photo yourself - it appears well done, with caliber, weights and velocities documented.
The puny wound channel of the 9mm is much more than a "marginal difference", the larger rounds leave nearly twice as much damage behind.


Everyone can decide for themselves...
Me? I'll take the wound channeling, penetration, expense, and capacity of the 40 over the rest.
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Old October 8, 2012, 05:01 PM   #18
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Ahhhh... Time to unsubscribe.
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Old October 8, 2012, 05:13 PM   #19
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The problem is you're basing your argument on a photo of the round's performance in ballistics gel. Actual real-world shootings have shown that, when it comes to actually putting an attacker down, the advantage a .40 has is marginal at best.

Nobody is arguing that the .40 doesn't have better terminal ballistics than the 9mm, we're just saying that the real-world difference isn't anywhere near as big as some people think it is.

9mm, .40, .45; with good hollowpoints they're all pretty close as far as performance and none are that great when it comes to putting the target down as quickly as possible. That's why I use an AR-15 for home defense.
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Old October 8, 2012, 06:53 PM   #20
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The problem is you're basing your argument on a photo of the round's performance in ballistics gel. Actual real-world shootings have shown that, when it comes to actually putting an attacker down, the advantage a .40 has is marginal at best.
I bolded the key word. Very marginal. They're all pea shooters. You need to start moving towards your full house 10mm, .357 mags, etc, before you're talking about a real increase in terminal effect. For a decisive increase? With practical weapons, we're talking a move up to long arms.

If someone thinks they're in a "different league" of terminal effect with .40S&W compared to 9mm, their understanding of the topic is very, very poor.

Quote:
Just look at this photo yourself - it appears well done, with caliber, weights and velocities documented.
The puny wound channel of the 9mm is much more than a "marginal difference", the larger rounds leave nearly twice as much damage behind.
As interpreted by a non-professional using the "eyeballing it" technique. Sounds empirical.
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Old October 8, 2012, 07:13 PM   #21
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Recoil with the small polymer guns is impressive to say the least. I wouldn't want to put more than a mag through the PM40.
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Old October 8, 2012, 08:46 PM   #22
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As interpreted by a non-professional using the "eyeballing it" technique. Sounds empirical.
At least I brought a picture - a informational and seemingly trustworthy one at that.
Its clear that there is a difference between popular auto ammo.
It doesnt matter if you think its important or not. The difference exists and its in the math.

I see the 40 as a advantage in pistols that I shoot well.
I'll take that advantage, whether it would matter or not.

This thread is about the PM40 vs the PM9 - some seem to have missed where I said the 9mm is my chosen round for the PM's (I own a PM9 and I dont think I'd care for a PM40.
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Old October 8, 2012, 09:01 PM   #23
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Quote:
The problem is you're basing your argument on a photo of the round's performance in ballistics gel. Actual real-world shootings have shown that, when it comes to actually putting an attacker down, the advantage a .40 has is marginal at best.
The gel is consistant - gives a good baseline comparison.
I think that the photo holds water; the picture on the right matches the numbers on the left.

Marginal at best?
Then why do many police departments use the 40? Its not cause its cheaper, or easier to shoot.

Even if it is just marginal.. I'll take it.
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Old October 8, 2012, 09:12 PM   #24
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Then why do many police departments use the 40? Its not cause its cheaper, or easier to shoot.
It's frequently chosen because it has better terminal performance than 9mm after passing through tough barriers, particularly auto glass. Such materials often plug the hollow point cavity and prevent the bullet from expanding, and may also strip away some of bullet material. A .40S&W bullet starts out larger and heavier, so it should punch a bigger hole and retain more weight after going through a hard barrier.

Barrier penetration is less of a factor in civilian shootouts because the usual goal of civilian SD is to stop the attack and/or buy enough time to escape- NOT to dig a determined and potentially suicidal BG out from behind cover.
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Old October 8, 2012, 09:18 PM   #25
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Also, a bit of terminology...

For the OP:

FYI, the "40" in .40S&W refers to 0.40 inches, not millimeters.

.40mm would be about the size of a sharpened pencil lead- not optimal for terminal performance.

40mm is a real military caliber, but the guns that fire it qualify as light artillery, not small arms. Google "Bofors gun". Not very concealable unless you count the inside of a truck trailer.
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