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P-40s and their owners rarely make the news.
Here's one who did.
Crawford entered the gas station just before midnight, pointed a loaded .357 revolver at Wetzel and demanded money, cigarettes and blunts. Wetzel gave him money, but when Crawford demanded more cigarettes, Wetzel told him he had to reach underneath the counter to get them, Zappala said.

Wetzel, a Vietnam War veteran, grabbed a Kel-Tec .40-caliber pistol, which he had a permit to carry, and shot Crawford twice in the chest, Zappala said.

"The clerk was scared because the robber wanted more and more items and (the clerk) did not have access to the safe," Zappala said.
http://www.pittsburghlive.com/x/pittsburghtrib/news/s_522402.html
 

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Off the original thread topic, I know, but the Pittsburgh article isn't all that 2nd Amendment-friendly.  I mean, the headline is that the clerk was "cleared", implying that there may have been a presumption of guilt in some people's minds.  Let me get this straight--a guy is robbing me at the point of a .357 Magnum revolver, and I might NOT have a right to shoot him?!?  Sorry to be a crank, but that scares me.   MARK
 

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markwillecho said:
Off the original thread topic, I know, but the Pittsburgh article isn't all that 2nd Amendment-friendly.  I mean, the headline is that the clerk was "cleared", implying that there may have been a presumption of guilt in some people's minds.  Let me get this straight--a guy is robbing me at the point of a .357 Magnum revolver, and I might NOT have a right to shoot him?!?  Sorry to be a crank, but that scares me.   MARK
Actually, I wouldn't take it that bad.  In the eyes of the law, if you shoot someone you have assaulted them (battered in some states) and if you kill them you have comitted homicide.  This is true whether you had a right to do so or not.  The question them becomes, well, did you have a right to do so.  "Self Defense" is a justification for the act, not something that makes you "innocent" of the act. It stops you from being charged (clears you), or it relieves you of the punishment for having comitted the act, but it doesn't take away the fact that you did the act.

-Scott
 

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Kudos to the clerk! Nice to see the 2nd in action.

Back on topic a little bit, I got curious about the barrel thickness claims of that one poster, so I got my new micrometer and grabbed my P11. Granted, I am really new with this mic, but here are my numbers:

ID of the barrel: 0.3565 in. (~9.05mm inside rifling grooves)
OD at narrowest point: 0.4555 in.

Assuming little or no operator error, that gives me a minimum thickness of 0.0990 in. The P40 is probably different, but not anywhere near 0.027 inches like that one guy claims. I'm leaning toward throwing the BS flag.

On the other hand, I've never seen a P40 barrel. Is it THAT different from the P11? I was assuming the same basic design with slightly different dimensions to accept the .40 round.
 

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leichliterk said:
Assuming little or no operator error, that gives me a minimum thickness of 0.0990 in.  The P40 is probably different, but not anywhere near 0.027 inches like that one guy claims.  I'm leaning toward throwing the BS flag.
Actually, one more step is needed to arrive at the wall thickness - divide the difference in measurements by 2. This will give a 0.0495" wall thickness. Still double the thickness reported.

I haven't run the numbers for hoop or longitudinal stress in this section, so I don't know where they would land on the range of reasonable allowable stresses. I don't have enough information as yet to do this - the pressure cited above may or may not be the pressure experienced at the section (due to the piston-like action of the projectile), don't know the temper of the alloy (ordinance steel is a null term), and don't know the impact characteristics of the material. My guess, however, would be that the stresses would compare favorably to to ultimate tensile strength of plain AISI4140.

That said, I doubt the anecdotal 'evidence' presented, and tend to believe the train of thought that hews to the 'too many returns from dissatisfied customers' reasoning.

BTW, I am an engineer that makes a living with piping stresses, etc. I mention that lest the respondent think I lack the necessary qualifications to begin the discussion.
 

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oakme2 said:
Pocket gun

You say clever story, not at all. Take any keltec 40 apart and measure the barrel thickness, it will be right at .027 inches. Now call any gunsmith and ask them to cut a barrel on a custom gun down to this extreme thin wall spec of .027. If he is not ignorant he will tell you no way, because it will be dangerous.  Also if you calculate the internal pressure, and find the numbers to calculate the strength of the steel at this thickness like an engineer would, the numbers would tell you that this design is prone to fail.  My gun blew the last bit of the barrel off. The barrel separated at the point where it is thin. If the management at Keltec was on the ball they would offer to buy all P40's back, and throw in a new P-11 to make them look good.
Like I said, please show me some evidence of the blown up pistols. So far, all we have is your "testimony" of what happened. And lets not forget, you are the guy saying the .357SIG barrels are unsafe too, in spite of the fact you know the walls are thicker. Did you read that part of my reply? It is rather inconvenient to get caught lying when you are trying to convince people of something based on your typed words alone. You have a credibility problem. Go back to selling SCCY knock-off garbage or whatever it is you do during the day.
 

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ChasF said:
[quote author=leichliterk link=1236524898/15#24 date=1238209681]Assuming little or no operator error, that gives me a minimum thickness of 0.0990 in.  The P40 is probably different, but not anywhere near 0.027 inches like that one guy claims.  I'm leaning toward throwing the BS flag.
Actually, one more step is needed to arrive at the wall thickness - divide the difference in measurements by 2.  This will give a 0.0495" wall thickness.  Still double the thickness reported.
[/quote]

That was a pathetic, [email protected]$$ mistake on my part! Wow. Can't believe I left off the last step. I'm not a mechanical engineer, for sure, but as a software engineer I definitely have enough math under my belt to know better than THAT!!! :(

OK, if everyone is sufficiently appeased, I'll stop groveling now.

Ugh. So embarrassed... :-[
 

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Little does anyone know, but if you have a P-40 the ammo to use is the Winchester 180 gr. Subsonic. Made for large silencer handguns such as (Beretta 92, Sig 226)ect. The .40 cal 180 gr. Subsonic is an ideal choice for the light weight P-40. Tames the beast, but is ideal for 25 yards and under. Problem is at this time in our history. Trying to find a box! :-/

http://www.ebr-inc.net/40S&WSubsonic.html

http://www.10-32supply.com/firearms/winchester/centerfireballistics.htm

http://www.americanhandgunner.com/CCT0907.html
 

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warthog said:
Little does anyone know, but if you have a P-40 the ammo to use is the Winchester 180 gr. Subsonic.  
I'd have to disagree with that.  For a 40 cal, the P40 is a short-chambered pistol with a short barrel.  Back in the day, old school KTOGers specifically advised against 180 grain ammo in the P40.  The longer AOL of the 180 grain stuff can cause some problems, some of which you really  don't want, like smilies and bullet set-back which can lead to an over-pressured round.

http://www.1bad69.com/keltec/p40-180gr.htm

Even if over-pressured 180 grain rounds weren't an issue, (maybe not in a subsonic), you are not going to get optimal performance from such a heavy bullet from the short barrel of the P40 - particularly, I think, in a subsonic loading.
 

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BlueWing said:
I sure can not figure out what they quit making that fantastic pistol, P-40.  I just bought a second one that looks like it has never been fired.  The ONLY negative with ANY Kel-Tec is that the stock sights make them shoot low.
?
I find as well that my P40 shoots low. You mention that "stock sights" make them shoot low. I am a newbie and am wondering if there are aftermarket sights that I can use to fix this?
 

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TxCajun said:
[quote author=warthog link=1236524898/15#28 date=1238373271]Little does anyone know, but if you have a P-40 the ammo to use is the Winchester 180 gr. Subsonic.  
I'd have to disagree with that.  For a 40 cal, the P40 is a short-chambered pistol with a short barrel.  Back in the day, old school KTOGers specifically advised against 180 grain ammo in the P40.  The longer AOL of the 180 grain stuff can cause some problems, some of which you really  don't want, like smilies and bullet set-back which can lead to an over-pressured round.

http://www.1bad69.com/keltec/p40-180gr.htm

Even if over-pressured 180 grain rounds weren't an issue, (maybe not in a subsonic), you are not going to get optimal performance from such a heavy bullet from the short barrel of the P40 - particularly, I think, in a subsonic loading.
[/quote]Ok. No 180s for the P-40 it is. I've never heard of such, but I will take your word for it.
 

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OK, I've run some numbers on this as suggested by oakme2.

My assumptions were:
1) the smallest OD is 0.4555" and the ID is 0.3565", which results in a wall thickness of 0.0495"
2) the pressure seen by the barrel is a constant 33 ksi (assumes the SAAMI figure is an actual pressure, and does not change while the bullet is in the barrel

Using the above, the hoop stress in the smallest section of the barrel is 118.8 ksi. SAE/AISI 4140 generally has minimum tensile strength of 125 ksi, and a minimum yield of 108ksi. Thus it can be seen that (for sustained pressure) the stress is less than the tensile strength of the material.

If the wall is actually the 0.027" claimed, the hoop stress goes up to 217.8 ksi, which may indeed cause some problem strength-wise. The actual scenario consists of a short duration impulse (yes, this is a redundant statement), so the material may be capable of withstanding the load anyway due to the pressure pulse propagation time in the material.

It should be noted that the KT barrels are hardened to about Rc47, so the actual strength capabilities may be quite a bit different from non-heat treated material.

If one assumes that the propellant gasses act in the barrel as a perfect gas expanding against a piston (bullet), then the pressure drops to about 8440 psi when the bullet gets 3 inches from the case bottom. Presumably this is about the same area where the minimum section occurs. At that point the hoop stress is 30.4 ksi for the 0.049" wall, and 55.7 ksi for the 0.027" wall - well within the capabilities of the material. This consideration is possible because the bullet is basically subsonic (for the expanding gas conditions) so the pressure wave can keep up with the bullet.

As can be seen, this is probably not the reason for the discontinuation of the P40. I find it hard to believe that any manufacturer would not launch an immediate and total recall of a known explosively dangerous product from just liability concerns. Also, if it really was as marginal as has been claimed, surely there would have been more 'energetic disassemblies' of the P40, and it would be well known.
 

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leichliterk said:
[quote author=ChasF link=1236524898/15#25 date=1238216262][quote author=leichliterk link=1236524898/15#24 date=1238209681]Assuming little or no operator error, that gives me a minimum thickness of 0.0990 in.  The P40 is probably different, but not anywhere near 0.027 inches like that one guy claims.  I'm leaning toward throwing the BS flag.
Actually, one more step is needed to arrive at the wall thickness - divide the difference in measurements by 2.  This will give a 0.0495" wall thickness.  Still double the thickness reported.
[/quote]

That was a pathetic, [email protected]$$ mistake on my part!  Wow.  Can't believe I left off the last step.  I'm not a mechanical engineer, for sure, but as a software engineer I definitely have enough math under my belt to know better than THAT!!!   :(

OK, if everyone is sufficiently appeased, I'll stop groveling now.

Ugh.  So embarrassed...   :-[[/quote]


Here is the deal, the P11 barrel ID is much smaller than the P40, the OD is the same both guns that makes the P11 have a thicker barrel. The 9mm bullet is .355 to .356 inches in dia. The 40 bullet is .400 to .401 inches in dia. making the wall of the barrel much thinner on the P40.  So bottom line is taking measurements of the much thicker P11 barrel has nothing to do with coming up with an accurate dimension for the P40. The numbers I gave were accurate in the previous posts.

The strength stated in the post according to wiki is 32,633 psi. That means that a piece of steel 1 x 1 x 1 inches will withstand 32,633 psi.  The steel on the P40 is .027 inches at the thinnest point.  The steel on the P40 barrel is much stronger than the steel Wiki listed more like 97,200 PSI. so if this stuff was 1 inch thick it could take 97,200 PSI for extended periods.  It would take computer program, or 2 pages of high level math to calculate the strength of the P40 barrel. These things are not easy for the average person to understand. The numbers say the P40 barrel is way to thin, and the P11 barrel while very thin too, is not in danger of separating. The SAAMI max pressure for the 40 S&W is 35000 psi. Don't forget to factor in heat, and pressure together. Along with the stress of the bullets friction. If you leave these out you will not get an accurate picture.

I am considering a law suite against Keltec, and I will not post any photos until after that is settled.


All of this can be verified easily, do some research, measure a P40 barrel, crunch some numbers, there is nothing like knowing the truth, and it is out there.
 

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Sir,
You are quite correct about the diameters. I inadvertently used the 9mm diameter in the calculation.

Due to the statements you have in the last post, I strongly urge you to consult with both a metalurgist and a product liability attorney before deciding to file a suit against Kel-Tec.

I am not a metalurgist, nor am I materials engineer. So I cannot speak to the behaviour of thin sections under impulse loads, nor can I address decisively the change in ultimate strength due to the heat treatment. If you check the materials tables used for pressure vessel design, though, you will see that 4140 generally has an ultimate strength of around 125,000 psi, and that the design allowables do not start reducing until above 400F.

As noted in my last post, if perfect gas behaviour is assumed for the combustion products the hoop stress in the barrel near the end (where the minimum section occurs) with the 0.027" wall thickness is only about 55,000 psi. So there should be enough material to withstand the force. I again urge you to have this verified by a metalurgist who can better address the materials properties before proceding with legal actions.
 

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Still waiting for pics.  Still waiting for evidence.  None is forthcoming.  oak2me = troll

Easy to tell when someone's first post on an enthusiast forum starts with:

oakme2 said:
Ok this is like droping a bomb on the minds of P40 owners.
Here is your "bomb"...

 

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Lurker38 said:
Not just a troll, but possible Scott D type material here.

::)


BTW, what's a law "suite"?
One of the first things a lawyer filing "suite" will advise is to shut your stupid mouth...... ESPECIALLY on bulletin boards about companies you are about to "sui." We can conclude from this that the consideration to file "suite" is comparable to my reveries about running for president or some fat guy in a cubicle doing data entry somewhere while dreaming of kicking Tom Brady's @ss and going off on a romp with Giselle Bundchen. The only difference is that me and that fat guy have sense enough not to bloviate about our fantasies to people whose only response will be to mock us.
 

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ChasF said:
Sir,
You are quite correct about the diameters.  I inadvertently used the 9mm diameter in the calculation.

Due to the statements you have in the last post, I strongly urge you to consult with both a metalurgist and a product liability attorney before deciding to file a suit against Kel-Tec.

I am not a metalurgist, nor am I materials engineer.  So I cannot speak to the behaviour of thin sections under impulse loads, nor can I address decisively the change in ultimate strength due to the heat treatment.  If you check the materials tables used for [highlight]pressure vessel design[/highlight], though, you will see that 4140 generally has an ultimate strength of around 125,000 psi, and that the design allowables do not start reducing until above 400F.

As noted in my last post, if perfect gas behaviour is assumed for the combustion products the [highlight]hoop stress [/highlight]in the barrel near the end (where the minimum section occurs) with the 0.027" wall thickness is only about 55,000 psi.  So there should be enough material to withstand the force.  I again urge you to have this verified by a metalurgist who can better address the materials properties before proceding with legal actions.
:cool:

Many moons ago I used to design those things for a living.

Agreed, the hoop stress is the determining factor here. IIRC the hoop stress is around twice what the longitudinal stress is. More or less. It is after all almost 30 years since I've crunched the numbers on a pressure vessel. Back then we didn't HAVE computers. That period was when we switched from Log Tables to EXPENSIVE simple calculators.

I'll put my confidence in the guys at KT that design these things for a living. ;)
 
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