PSA - .40 S&W in a 10mm...Don't do it!

ZeSpectre · September 26, 2008, 12:23 PM

Had a guy at the range last night who was asking about shooting .40 S&W in the new 10mm (edit: Glock 20) semiauto he'd just bought. Normally I would leave the range guys alone but when one of them said "don't see why not" I had to jump in.

I know this topic has been covered before but folks, do NOT shoot .40 S&W in a 10mm gun.

See this article
http://www.thegunzone.com/10v40.html

Have a safe weekend
Ze

Tamara · September 26, 2008, 12:27 PM

To clarify, it's peachy keen to shoot .40S&W in a 10mm Auto REVOLVER (using moonclips).

Not so much in a semiautomatic...

ZeSpectre · September 26, 2008, 12:31 PM

Oops, yes. I should have made that point clear.
The gun was a Glock G20 Semi-Automatic.

Wuchak · September 26, 2008, 01:19 PM

I cannot access the link from work but I was wondering if a .40 in a 10mm chamber would ever fire. Since semi-auto cartridges space on the case mouth wouldn't the force of the firing pin just push the cartridge forward in the chamber?

SGHOTH · September 26, 2008, 02:25 PM

Quote:

I was wondering if a .40 in a 10mm chamber would ever fire

In most guns the extractor will hold the cartridge firmly enough for it to fire. I do not think this is good for the gun or the operator. Just because you may get away with it in the short term doesn't make it a good idea.

ZeSpectre · September 26, 2008, 03:11 PM

Quote:

I was wondering if a .40 in a 10mm chamber would ever fire. Since semi-auto cartridges space on the case mouth wouldn't the force of the firing pin just push the cartridge forward in the chamber

Yes most will fire and here's what seems to happen.
-The round chambers "loosely" (picture a shotgun held loosely against the shoulder).
-The extractor typically holds the round back enough against the breech face that the firing pin can ignite the primer.
-This slams the case back HARD against the breech face (again the shotgun not held tight to the shoulder analogy) and probably usually rebounds forward again at least once, battering the breech face, the firing pin, and the extractor. (extractors will not hold up long to this kind of abuse).
-This also has the potential to create an "unsupported case" situation and thus a potential KABOOM down the magazine well if the brass were to let go.

**JohnKSa** · September 26, 2008, 09:07 PM

Even worse, in a semi-auto there's a "step" at the front of the chamber. The .40 bullet gets a running start at that step and may not hit it perfectly centered since the chamber is bigger than the bore. That can shave bullet material and leave it to build up on the step. Eventually that material can build up enough to cause an obstruction...

That doesn't happen in revolvers because revolver chambers taper gently instead of having an abrupt step at the front of the chamber.

HK123 · September 26, 2008, 09:21 PM

Sounds like someone was trying to cheap out on ammo.

ZeSpectre · September 27, 2008, 03:35 PM

and can you believe it, I posted this same warning on another board and had people arguing with me that it "wasn't a big deal"

Well, I guess somebody has to keep the reconstructive surgeons in business.

buzz_knox · September 27, 2008, 04:24 PM

I had a shop owner tell me this was perfectly acceptable. Needless to say, I never bought anything from him.

September 26, 2008, 12:23 PM	#1
ZeSpectre Senior Member Join Date: June 4, 2007 Location: Shenandoah Valley Posts: 3,276	PSA - .40 S&W in a 10mm...Don't do it! Had a guy at the range last night who was asking about shooting .40 S&W in the new 10mm (edit: Glock 20) semiauto he'd just bought. Normally I would leave the range guys alone but when one of them said "don't see why not" I had to jump in. I know this topic has been covered before but folks, do NOT shoot .40 S&W in a 10mm gun. See this article http://www.thegunzone.com/10v40.html Have a safe weekend Ze

September 26, 2008, 12:27 PM	#2
Tamara Moderator Emeritus Join Date: March 11, 2000 Location: Indianapolis, IN Posts: 16,002	To clarify, it's peachy keen to shoot .40S&W in a 10mm Auto REVOLVER (using moonclips). Not so much in a semiautomatic... __________________ MOLON LABE! 2% Unobtainium, 98% Hypetanium. The Arms Room: An Online Museum.

September 26, 2008, 09:07 PM	#7
JohnKSa Staff Join Date: February 12, 2001 Location: DFW Area Posts: 24,990	Even worse, in a semi-auto there's a "step" at the front of the chamber. The .40 bullet gets a running start at that step and may not hit it perfectly centered since the chamber is bigger than the bore. That can shave bullet material and leave it to build up on the step. Eventually that material can build up enough to cause an obstruction... That doesn't happen in revolvers because revolver chambers taper gently instead of having an abrupt step at the front of the chamber. __________________ Do you know about the TEXAS State Rifle Association?

September 26, 2008, 12:31 PM	#3
ZeSpectre Senior Member Join Date: June 4, 2007 Location: Shenandoah Valley Posts: 3,276	Oops, yes. I should have made that point clear. The gun was a Glock G20 Semi-Automatic.

September 26, 2008, 01:19 PM	#4
Wuchak Senior Member Join Date: June 1, 2007 Location: Shawnee, KS Posts: 1,093	I cannot access the link from work but I was wondering if a .40 in a 10mm chamber would ever fire. Since semi-auto cartridges space on the case mouth wouldn't the force of the firing pin just push the cartridge forward in the chamber?

September 26, 2008, 09:21 PM	#8
HK123 Junior member Join Date: May 29, 2008 Posts: 1,172	Sounds like someone was trying to cheap out on ammo.

September 27, 2008, 03:35 PM	#9
ZeSpectre Senior Member Join Date: June 4, 2007 Location: Shenandoah Valley Posts: 3,276	and can you believe it, I posted this same warning on another board and had people arguing with me that it "wasn't a big deal" Well, I guess somebody has to keep the reconstructive surgeons in business.

September 27, 2008, 04:24 PM	#10
buzz_knox Senior Member Join Date: December 2, 1999 Location: Knoxville, in the Free State of Tennesse Posts: 4,190	I had a shop owner tell me this was perfectly acceptable. Needless to say, I never bought anything from him.