What would happen?

Qtiphky · April 20, 2009, 04:38 PM

A buddy just informed me that he shoots 40 S&W out of a Glock (model unknown) in 10mm caliber.

While I understand that they shoot the same diameter bullet, the case lengths are different. The 40 is .85 inches and the 10 is .992 inches. Wouldn't this cause ejection problems and functioning problems?

Sevens · April 20, 2009, 05:09 PM

Given that the two calibers run at about the same pressure, at least there isn't a significant risk of it coming apart. The two big problems that I would see happening is that the original 10mm chamber would get reefed up by the shorter .40's being fired short of it, and the other problem is that cases would have to be "suspended" in front of the firing pin held in place only by the tension of the extractor... otherwise, they'd fall too deeply in the chamber to get properly hit by the firing pin.

.40 barrels are widely available for both the G20 and G29, the two 10mm models that Glock makes. For about $100 or $120, he could be doing this properly, more accurately, much more safely and without screwing up his OEM barrel.

As well, it's kinda silly to shoot .40 ammo in a pistol as beefy as a G20/G29... you can have a slimmer and easier handling, more "trim" package if you really want .40 by buying one of the Glock .40s. Seems like he's too cheap to buy 10mm ammo for his 10mm pistol and is feeding it .40 instead. Not smart.

April 20, 2009, 04:38 PM	#1
Qtiphky Senior Member Join Date: December 11, 2008 Location: Upper Michigan, above the Mackinac Bridge Posts: 568	What would happen? A buddy just informed me that he shoots 40 S&W out of a Glock (model unknown) in 10mm caliber. While I understand that they shoot the same diameter bullet, the case lengths are different. The 40 is .85 inches and the 10 is .992 inches. Wouldn't this cause ejection problems and functioning problems?

April 20, 2009, 05:09 PM	#2
Sevens Senior Member Join Date: July 28, 2007 Location: Ohio Posts: 11,756	Given that the two calibers run at about the same pressure, at least there isn't a significant risk of it coming apart. The two big problems that I would see happening is that the original 10mm chamber would get reefed up by the shorter .40's being fired short of it, and the other problem is that cases would have to be "suspended" in front of the firing pin held in place only by the tension of the extractor... otherwise, they'd fall too deeply in the chamber to get properly hit by the firing pin. .40 barrels are widely available for both the G20 and G29, the two 10mm models that Glock makes. For about $100 or $120, he could be doing this properly, more accurately, much more safely and without screwing up his OEM barrel. As well, it's kinda silly to shoot .40 ammo in a pistol as beefy as a G20/G29... you can have a slimmer and easier handling, more "trim" package if you really want .40 by buying one of the Glock .40s. Seems like he's too cheap to buy 10mm ammo for his 10mm pistol and is feeding it .40 instead. Not smart. __________________ *Attention Brass rats and other reloaders:* I really need .327 Federal Magnum brass, no lot size too small. Tell me what caliber you need and I'll see what I have to swap. PM me and we'll discuss.