IIRC, "gas operated pistols" are different than their rifle brethren. With rifles and shotguns, the gas is tapped and this pressure is used to cycle the action via a piston (AK) or directly (M-16). The "gas operated" pistols I'm familiar with Desert Eagle, H&K P9S, H&K P7, use the gas as part of the locking system.
Full power cartridges such as 9, 40, or 45, require a locked breech to protect the shooter from the pressures of the cartridge. It is necessary to allow the pressure in the chamber to drop before cycling the action. When the barrel travels backward on a Browning action, the system is actually "unlocking."
Some lesser calibers, like 380, don't require a locked breech and are more accurately defined at "blowback." Sub machine guns in real calibers are blowback as well because the bolt is so much heavier than the equivalent pistol.
"Gas operated" pistols use the gas pressure to delay the cycling of the slide until pressures drop to an acceptable level. This means that the barrel is fixed and the pistol capable of remarkable accuracy, at least the HK's.
The only drawback, at least with the P7, is that the area that traps the gas heats quickly with extended firing, meaning one has to let the gun cool occassionaly. This isn't typically an issue except in classes that fire large numbers of rounds.
There are a few exceptions to this. The one I immediately think of is the "arm gun" that was developed for pilots. It was basically a handgun, used 223 ammo, M-16 magazines, and a true gas system.
[This message has been edited by ajp3jeh (edited 11-11-2001).]
Thanks a lot for the information. I was looking at the specs on the Desert Eagle and P7 when I read that they were "gas operated".
I'm obviously a novice, but there's something a little bit more comforting about knowing the mechanical operation of the guns/rifles I own. I think it's a good idea to know how they all work even if it's just to a tiny degree.
...Or should I just worry about whether or not the gun goes 'bang' when I pull the trigger?..
Come on, ajp, let's give the man the straight poop. True, the H&K P7 operates by what is best called gas retarded blowback. There is nothing holding the slide forward but its own inertia, the recoil spring, and gas in a cylinder under the barrel which is pressurized immediately after the bullet leaves the chamber.
However, the Desert Eagle is gas *operated* more like an M1 Carbine than any other gun I can think of. The slide is locked shut by a rotating bolt. When the bullet passes the gas port near the muzzle, gas pressure forces a piston to the rear, which kicks the slide back. The bolt rotates to unlock and the action opens. See http://zvis.com/dep/depmantmpl.shtml?../images/guns/depman/depman04.jpg
The H&K P9S has NO gas handling parts. It has the same roller lock system as the H&K rifles. Whether that is recoil operation or delayed blowback or a third system altogether is still sometimes debated. It is not gas operation except that it is gas pressure in the chamber that gets things moving, the same as with conventional recoil or blowback guns.
[This message has been edited by Jim Watson (edited 11-12-2001).]
Other "gas retarded blowback" pistols are the Heritage Stealth, the south african Vektor CP1, an obscure Norinco model (don't remember the name), and (the first one?) the Steyr GB.
I think other gas operated pistols were the Wildey and the AutoMag.
To continue this nickpicking, there are also some successful blowback guns in 9x19, like the Astra 600 and the HK VP70, contrary to what most people think the recoil spring is not too strong or the slide too heavy.
Thanks for the added obscure gas ops.
The Wildey has a ring piston similar to Husqvarna prototypes Jeff Cooper described in 1975.
The Automag, however, is recoil operated.
And the Colt Gold Cup .38 Special is blowback.
Yeah, I have read about those. Even the magazine articles admitted the NCG was ammo and magazine sensitive. My FLG is fascinated by them, but I have already screwed up one gun with the Jarvis Kam-Lock linkless recoil system and am not willing to gunea-pig another gimmick. Unless it would fit the mill cut made for the Jarvis contraption. Hmmmm.