Is it worth it to upgrade from a PM 9 to a PM 40???


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Prosser
March 29, 2010, 01:24 AM
Hi
I'm wondering if the PM 40 provides enough additional punch out of that short barrel to be worth moving up from the PM 9?

Facts, opinions, ballistic information?

Thanks

P

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MICHAEL T
March 29, 2010, 01:36 AM
My self I would keep the 9mm I think a 9mm with good ammo will do what needs to be done. I don't like the recoil of a 40 at all.

desert gator
March 29, 2010, 01:38 AM
^^^agreed. I feel just as safe with a pm9 and it's twice as fun to shoot recreation wise.

Full Metal Jacket
March 29, 2010, 02:11 AM
i would keep +p in 9, and be confident with that. :)

NG VI
March 29, 2010, 02:53 AM
9mm is a fantastic defensive caliber these days, especially with all of the wonderfully designed JHP ammunition available. Pick something good and practice.

My first subcompact was a Glock 27, fantasting gun, but noticeably heavier than the Kahr PM series. I don't think I'd appreciate .40 out of anything smaller or lighter than that Glock.

Federal 147+P HST is my favorite 9mm carry load, and would be pretty ideal for a shorter barreled pistol like the Kahr. 147s as a rule have more stable velocity figures going from shorter to longer barrels and vice versa, and are designed to expand under much lower velocities than a comparable 115 or 124 grain bullet.

So to some it is counterintuitive, but a heavy for caliber bullet is actually better for a short barreled gun than trying to go fast and light.

JLaScala
March 29, 2010, 02:56 AM
I personally have never been a big fan of 40. Has all the recoil of 45acp with the stopping power of 9mm. At least with the 9mm, ammo is cheaper, and you get higher capacity.

Prosser
March 29, 2010, 06:50 AM
I was considering a new gun, about 670, in Kali, with double tap ammo...

LRS_Ranger
March 29, 2010, 07:28 AM
I would go with the 9mm.. In the same sized gun you will find that 9mm will allow you to shoot faster and generally more accurately (going for speed) than the 40. Plus ammo is cheaper and you will be able to practice more. With all the high-tech bullets that are out now, the 9 is plenty deadly. The key is shot placement. If you can't shoot it as well, the 40 will be worse despite it's higher energy.

hammerklavier
March 29, 2010, 11:59 AM
Get both.

xXxplosive
March 29, 2010, 12:04 PM
I'd forget about the .40 and just move up to what get's the job done....
.45ACP you'll toss that 9mm.

gofastman
March 29, 2010, 12:08 PM
NG VI I'm not arguing with you, but could you sight sources on this info? I would like to read more about the physics involved in that phenomenon.

and screw the 45ACP :neener:

NG VI
March 29, 2010, 02:50 PM
Gofastman I'm searching through the old battlefield, Caliber Corner on Glocktalk, where this was explained, and where sources were cited. I'll put it up when I find it.

outerlimit
March 29, 2010, 03:09 PM
If you carry some form of 124gr +P jhp in the PM9 you're doing pretty good defensive wise for a pocket gun. I like the Ranger 124gr. +P load and a spare 8rd in weak side pocket. I'd forget about the PM40. Yeah, I'd rather have a .45acp, but it don't fit in my pocket. I wish they had made the PM45 smaller, and without that god awful plastic floorplate. A 4+1 package with 6rd extended spare mags would be great. I'd even go for a metal frame version of that.

NG VI
March 29, 2010, 03:16 PM
Alright, here it is, well one of the many threads that goes over it anyway.

http://glocktalk.com/forums/showthread.php?t=854713&highlight=short+barrel+147&page=3

Check out post #60-61, post #68 has the name of the fellow from Winchester who wrote the email. Page 2 of that thread has a pair of pictures with kind of an index card of expanded 9mm JHP, from almost every manufacturer. Some mean looking bullets.

outerlimit
March 29, 2010, 03:42 PM
You might consider a TMJ type bullet in the 125gr. range and I think you'll generally get the same type of wounding effect as a 147gr. jhp out of a short barrel. Generally I'm speaking about a jacketed bullet with a flattened cone as opposed to a rounded one. This type of bullet is fairly popular in .40 target ammo, but not as much in 9mm and .45acp.

Manco
March 29, 2010, 03:49 PM
Gofastman I'm searching through the old battlefield, Caliber Corner on Glocktalk, where this was explained, and where sources were cited. I'll put it up when I find it.

That'll be really interesting to read. A great many people seem to believe the opposite--that lighter bullet weights work better out of short barrels because they'll maintain a higher speed--but I think that most of them are focused on attaining maximum JHP expansion rather than considering terminal performance as a whole. This subject has come up on this forum a number of times, and the intuitive explanation that I've always found most convincing (probably because I made it up ;)) is that lighter bullets need more powder to generate more gas in order to keep up with the momentum of heavier bullets, and that much of this additional gas will go to waste in a short barrel. The reason that more gas--and therefore total energy--is needed is that momentum varies proportionally with both mass and velocity, while energy varies proportionally with mass and the square of velocity, meaning that it is far easier to increase or maintain momentum by using a heavier bullet than by increasing velocity, making heavier bullets ideal for more limited equipment such as a short barrel. I'd sure like to see what others have to say about this in terms of physics.

outerlimit
March 29, 2010, 03:52 PM
I agree with you Manco. After all, there's a reason why a standard pressure 158gr. .38spl recoils harder than a 110-125gr. +P that has more energy.

Expansion is a side issue if overall performance is generally not that great.

Manco
March 29, 2010, 04:02 PM
Alright, here it is, well one of the many threads that goes over it anyway.

http://glocktalk.com/forums/showthread.php?t=854713&highlight=short+barrel+147&page=3

Check out post #60-61, post #68 has the name of the fellow from Winchester who wrote the email. Page 2 of that thread has a pair of pictures with kind of an index card of expanded 9mm JHP, from almost every manufacturer. Some mean looking bullets.

Oh, I must have responded to a stale version of this thread because I didn't see your post. It's interesting how Paul Nowak, the designer of the ammunition, I believe, basically gives the same physical explanation as I did from a completely different direction and point of view. It seems that theory and practice are both in agreement in favoring heavier bullets in short barrels.

Bullseye_shooter
March 29, 2010, 04:04 PM
Due to the small dimensions of the PM series the 9mm is a better suited cartridge. Its all about shot placement anyway, a .40 is not going to drop an attacker any faster unless you make your shots count. Stay with the PM9 and loaded it up with some Extreme Shock frangibles and that will be more than enough.

NG VI
March 29, 2010, 04:06 PM
That and the lighter bullets drop off in speed, and also gain speed, much more readily than heavy for caliber bullets. If you're using a 6" barrel, the difference in speed between a 124+P or +P+ and a 147 or even 147+P is going to be drastically different than the speed difference between the two loads in, say a 3.5" barrel.

And the lightweights are designed for speed, so they have to be tougher in order to hold together at the higher speeds than the heavies, which are much better suited to expansion at slower than intended velocities.

I personally think a lot of it has to do with people continuing to stick by the old, sort of kind of accurate for 1988 1000 FPS to expand or not at all rule of thumb. Doesn't work that way in 2010, and it hasn't worked that way since all those wonderful redesigns of JHP bullets that took place over the course of the 1990s. All the premium 147 bullets are superb expanders now, generally they are at the head of the class since designers have figured out how to use the additional weight and material of the heavy bullets to get a wider possible expansion.

And have you guys looked at a fully expanded 124 grain bullet? They are like a fat disc! A 147 that expands to the same diameter or even a little bit wider will have more of its core left behind the frontal area of the bullet, which I can only imagine would greatly assist the bullet in maintaining its path through the target.

Strahley
March 29, 2010, 04:20 PM
I'd forget about the .40 and just move up to what get's the job done....
.45ACP you'll toss that 9mm.

They will ALL get the job done if you do your part, and they will all fail to get the job done if you don't

Stick with the 9mm IMO

RyanM
March 29, 2010, 04:32 PM
I've got an MK40. Personally, if I were moving to a lighter PM gun, I'd make it a PM9 rather than a .40 or .45. That light of a gun would be hard to get follow-up shots with in a heavier caliber.

Just in terms of ballistics, here's some links:

Review of an MK40 http://www.kahr.com/PA-1B/handguns102799.html
Versus a PM9 http://www.kahr.com/PA-1B/review_ch_0902.html

The MK40 does pretty respectably across a chronograph. But it kicks a little bit. I don't think a PM40 would be much fun to shoot at all.

NinjaFeint
March 29, 2010, 04:42 PM
I am very comfortable with my PM9 and would not get a PM40. I carry it with either +P Gold Dots or +P DPX. I wouldn't mind picking up a T40 (much more shootable than PM40) to carry during the winter but I can't ever find the T series for sale.

The Lone Haranguer
March 29, 2010, 10:51 PM
I have a PM9 myself. IMO:

I'm wondering if the PM 40 provides enough additional punch out of that short barrel to be worth moving up from the PM 9?


A bullet that big in a gun that small is certain to hurt on both ends. If it is uncomfortable or even painful to shoot, you will not want to practice with it.

MattTheHat
March 29, 2010, 10:54 PM
I don't care much for the 10mm Kurz. In fact, I don't currently own anything chambered for it.

Now, "real" 10mm, that's another story all together! :)


-Matt

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