Gas Actuated vs. Recoil

[Diesle]

Looking for some enlightenment to the differences between the 2 sytems. Inherent drawbacks or benifit from each method.

Do particular rounds always mean that the gun it fires from will use one method or the other.... Stuff like that.

Diesle

 

[Navy joe]

I'm not real smart on gas pistols, somebody will help. I think the big drawback to gas is reliability. Foul the port and you have problems. Rifles running at higher pressures tend to be more self cleaning. I don't imagine lead bullets are good for the port either. I'm not sure, but in a recoil gun you can use loads of radically different power just by changing springs, don't think it's that simple with gas.

The gas advantge is that you can have a fixed barrel which should lead to more potential accuracy.

I don't think that certain rounds are made with one or the other in mind. Example is 9mm. In all kinds of recoil operated arms, and some gas retarded ones like the P7. Even blowbacks if you're into fugly guns.

 

[Tamara]

To further complicate matters, do you mean "gas operated" (Desert Eagle) or "gas-delayed blowback" (P7, Stealth, GB, CP1)?

In the first, the gas that is tapped off the barrel is used to operate the bolt/slide, just like in a gas-operated rifle.

In the second, the tapped gas is used to hold the slide closed against its own recoil until the bullet has left the barrel.

 

[Diesle]

I think what confuses me is that, in my mind, it seems that every handgun would operate naturally on a recoil principal. I.E. the detonation or the cartridge and the subsequent forward movement of the bullet, naturally produces a rearward force on the case. Since that rearward force should always exist, why would you need anything be recoil to operate the auto loading mechanisms? Is it the momentum of the case that actuates the mechanism before it is ejected...?

I cant connect the dots...


Diesle

 

[Flying V]

Blowback guns rely on case momentum pushing against a slide or bolt. Examples - Makarov, Ruger Mk II, or most other low-power autopistols. In a blowback gun, the barrel is fixed to the frame and the breech is not locked.

Recoil guns use the momentum imparted to the barrel, which moves backwards, taking a slide or bolt with it. When the barrel reaches the limit of its rearward travel, the slide or bolt unlocks and continues rearward. Examples: 1911, Glock 19, Beretta 92.
In a recoil gun, the barrel moves and the breech is locked.

Gas guns rely on propellant gas passing through a small port and driving a piston which pushes a bolt carrier to the rear. The bolt carrier has a cam of some sort to rotate or tilt the bolt in and out of lockup. Examples: Desert Eagle, Wildey. In a gas gun, the barrel is fixed and the breech is locked.

Delayed blowback guns rely on case momentum as do blowback guns, but the slide or bolt must overcome mechanical disadvantage before moving to the rear, as opposed to plain blowback in which only the mass of the slide/bolt and the stiffness of a spring resist movement to the rear. Examples: some H&K model whose designation I can't recall at the moment. The G3 rifle is delayed blowback. In a delayed blowback gun, the barrel is fixed and the breech is locked.

Gas-retarded guns rely on case momentum as do blowback guns, but propellant gas passes through a port and resists the rearward motion of a piston connected to the slide. Examples: HK P7, the AMT .22 Mag pistol. In a gas-retarded gun, the barrel is fixed and the breech is not locked.

 

[mete]

The force of the expanding gas pushes the bullet out the barrel and has equal force against the bolt ( usually the slide). In a low power cartridge like a 22 the weight of the slide and the recoil spring easily handle force. In higher power cartridges blowback operation would require a very heavy slide and very strong recoil spring. Therefore various designs have been created to solve this. These include locked breach of the colt/browning type, rotating barrel (CZ 24 etc) or delayed blowback which include the fine reminton M51 ( momentum block) and the equally fine P7 (gas delayed). There are other effects , for example if you fire different designs in the same cartridge the apparent recoil is different due to different time/force curves. In 380 the blowback Hsc is worse recoil than the locked breach CZ-24 but the best is the remington M51, delayed blowback.

 

[9mmepiphany]

i think the block to connecting the dots has to do with the need to have a locked action as opposed to a free action (blowback, held closed by the recoil spring only)

the locked (or delayed) actions are only needed for higher pressure/powered loads. the action needs to remain closed until bullet leaves/pressure drops. you can accomplish this with a blowback action but it requires a very heavy recoil spring...think astra 600 (9mm) or detonics pocket 9 (9mm also) or M3 grease gun (.45)

 

[Handy]

Recoil pistols, being so common, are considered "natural" and simple. Yet a rifle with a floating barrel seems a little absurd, despite some good efforts in the past.

The best system, in my opinion, is mechanically delayed blowback. This design is reliable, tough, super accurate and clean. It works well in any caliber, pistol or rifle. And the weapon does not lose accuracy as the moving parts wear.