Experienced opinion wanted on Glock 20, 10mm - Page 2

**JohnKSa** · November 3, 2012, 09:42 PM

Generally speaking, while it is possible to safely shoot a shorter round that is similar or lower pressure in a REVOLVER, it is never a good idea to shoot any round in an autopistol other than the specific round that the autopistol is made for.

While revolvers tend to be chambered for cartridges that headspace on the rim, autopistols are generally chambered for cartridges that headspace on the case mouth. When a shorter case is used, the cartridge headspaces on the extractor.

The extractor isn't designed for that and so it takes more stress than it should. In addition, it may allow the case to float forward farther than it should, creating excess headspace and the possibility of pierced primers.

HOWEVER, that is really a fairly minor issue. The real reason it's a bad idea to fire short cartridges in an autopistol chamber is because of the way autopistol chambers are designed.

Revolver chambers have a taper at the front of the chamber and then a taper called the forcing cone at the beginning of the barrel. A bullet fired from a shorter cartridge will be guided gracefully into the bore.

Autopistols have sharp step at the front of the chamber where the case mouth is designed to fit. If the cartridge is significantly shorter than the chamber then the bullet passes that sharp step and probably passes it off center somewhat since the chamber is typically bigger than the bore.

Material will shave off the bullet when that happens and that shaved material can build up at the front of the chamber. If that goes on long enough, you can get enough of a buildup to cause a partial obstruction and that can destroy the firearm.

Mrgunsngear · November 3, 2012, 10:15 PM

Quote:

I originally e-mailed plouffedaddy directly about this rather than resurrect an old thread, but he said a lot of people have the same questions and to repost it on the thread that led me to message him. So....here it is!

Good work

John broke it down much better than I did though; good information there on why the guns can fail after doing this for a prolonged period (where I was trying to go in my earlier email).

SerenityNetworks · November 4, 2012, 08:45 PM

Thank you for the great information.

Drew

NRA Life Member
------------------------
"There are some ideas so preposterous that only an intellectual will believe them." - Malcolm Muggeridge

November 3, 2012, 09:42 PM	#26
JohnKSa Staff Join Date: February 12, 2001 Location: DFW Area Posts: 24,975	Generally speaking, while it is possible to safely shoot a shorter round that is similar or lower pressure in a REVOLVER, it is never a good idea to shoot any round in an autopistol other than the specific round that the autopistol is made for. While revolvers tend to be chambered for cartridges that headspace on the rim, autopistols are generally chambered for cartridges that headspace on the case mouth. When a shorter case is used, the cartridge headspaces on the extractor. The extractor isn't designed for that and so it takes more stress than it should. In addition, it may allow the case to float forward farther than it should, creating excess headspace and the possibility of pierced primers. HOWEVER, that is really a fairly minor issue. The real reason it's a bad idea to fire short cartridges in an autopistol chamber is because of the way autopistol chambers are designed. Revolver chambers have a taper at the front of the chamber and then a taper called the forcing cone at the beginning of the barrel. A bullet fired from a shorter cartridge will be guided gracefully into the bore. Autopistols have sharp step at the front of the chamber where the case mouth is designed to fit. If the cartridge is significantly shorter than the chamber then the bullet passes that sharp step and probably passes it off center somewhat since the chamber is typically bigger than the bore. Material will shave off the bullet when that happens and that shaved material can build up at the front of the chamber. If that goes on long enough, you can get enough of a buildup to cause a partial obstruction and that can destroy the firearm. __________________ Do you know about the TEXAS State Rifle Association?

November 4, 2012, 08:45 PM	#28
SerenityNetworks Senior Member Join Date: February 13, 2012 Location: Allen, TX Posts: 416	Thank you for the great information. Drew NRA Life Member ------------------------ "There are some ideas so preposterous that only an intellectual will believe them." - Malcolm Muggeridge