Blowback vs Recoil - How do they differ?

[SoCal Gunner]

If a pistol claims to be blowback operated, how is that different from recoil operated? Feel free to throw gas operated into the discussion as well.

[kdm]

From MidwayUSA's Guntec dictionary: http://www.midwayusa.com/guntecdicti..._source=guntec

Definition for "recoil operated action" : A type of action found in some automatic and semiautomatic firearms in which the force of the barrel moving rearward due to recoil cycles the bore cycles the firearm. Generally, the barrel, due to the recoil spring, moves back into the forward position faster than the also forced backwards breechblock. Thus, when the breechblock moves forwards, it strips a new cartridge from the magazine and chambers it in the now resting barrel.

Definition for "blowback action" : An action characterized by a system where the pressure created by the combustion of the cartridge forces the slide open when the firearm is fired and after firing, the weight of the hammer, slide, recoil spring, and other parts combine to return the slide to the closed position. No mechanical locking system is used; found in automatic and semi-automatic firearms.

Definition for "gas-operated firearm" : An autoloading firearm that utilizes the expanding gases from a fired cartridge to push back the bolt and extract the fired cartridge. Gas-operated firearms are widely used in autoloading pistols, rifles, and shotguns.

[littlejake]

Blowback does not operate from a locked breech. The recoil spring, and the slide inertia, are the only forces holding the breech closed. Blowback is only used for lower power cartridges -- the .380 auto being about the most powerful using blowback. Blowback pistols will typically give you a sharper rap in the hand that the same cartridge in a locked breech pistol.

John Browning invented most of the designs for a locked breech pistol, where the barrel is locked into the slide in battery. His link design (such as found in the 1911) keeps the breech locked during the time the bullet is exiting the barrel, allowing chamber pressure to expel out the muzzle prior to the breech unlocking. Recoil operates the Browning design.

[Swift Justice]

Pretty rare to see large caliber pistols in a blowback design, but one that comes to mind is the HK VP70Z in 9mm.

The FN 57 is also a blowback, but I guess it would qualify as a small caliber...

[JTROKS]

Recoil operated is the barrel moving back with the bolt to keep them locked up or closed to provide time to allow pressures to drop at a safe level to where the empty case can be safely ejected. The forward movement will have the barrel move forward first then the bolt stripping a fresh round from the magazine. As with any moving parts, accuracy will suffer if the lock-up position is not consistent.

Gas operated firearms will have port(s) usually midway or pass midway of the barrel to direct some of the hot gasses to a gas tube in which will either be a direct impingement or piston or rod to unlock the bolt sending it to the rear. Springs are used to send the bolt and piston forward, they also help the bolt strip a fresh round feeding it to the chamber ready for the next shot.

There are other types of locking the bolt and barrel together such as roller lock, but their main function is to simply decrease pressures to a safe level.

[9mmepiphany]

blowback handguns usually stop at .380 due to the pressure of the round involved. the larger calibres that come to mind are the Astra 600, VP70Z, Detonics Pocket 9 (9mm) and the AMT Backup (.45)

gas operation in handguns is usually used to keep the slide closed until the gas presure drops, than it becomes a blowback operated handgun the H&K P7 (9mm & .40) and Steyr GP (9mm) come to mine. the gas operated actions described above usually apply more to rifle actions with the obvious exceptions being the AutoMag (.44 AMP)

[wu_dot_com]

blowback handguns usually stop at .380 due to the pressure of the round involved. the larger calibres that come to mind are the Astra 600, VP70Z, Detonics Pocket 9 (9mm) and the AMT Backup (.45)

gas operation in handguns is usually used to keep the slide closed until the gas presure drops, than it becomes a blowback operated handgun the H&K P7 (9mm & .40) and Steyr GP (9mm) come to mine. the gas operated actions described above usually apply more to rifle actions with the obvious exceptions being the AutoMag (.44 AMP)

and the desert eagle.

[SoCal Gunner]

Thanks for the responses. I guess what is kind of confusing is that in common terms, BOTH are acting on the force of recoil - no?
So could this be simplified to blowback = fixed barrel, non locked and recoil = locked and moving?

[Old4eyes]

Here's a link where a guy does a great job of explaining blowback vs locked breech -

http://yarchive.net/gun/pistol/blowback_vs_locked.html

[TKM]

It's just the way that the forces involved are used.

Blowback acts entirely upon the spring pressure and inertia of the slide.

Works fine(ish) for rimfire and low power centerfire rounds.

Other action types use mechanical and/or gas mechanisms to somewhat delay and redirect the forces to the same end but can do so safely with much more powerful cartridges.

[tonelar]

From MidwayUSA's Guntec dictionary: http://www.midwayusa.com/guntecdicti..._source=guntec

...
Definition for "gas-operated firearm" : An autoloading firearm that utilizes the expanding gases from a fired cartridge to push back the bolt and extract the fired cartridge. Gas-operated firearms are widely used in autoloading pistols, rifles, and shotguns.

That's wrong... very few autoloading pistols are gas operated.

[JTsanchez]

My 380 PPK/S is blowback and painful to shoot, dead accurate, but painful.

[JTROKS]

Thanks for the responses. I guess what is kind of confusing is that in common terms, BOTH are acting on the force of recoil - no?
So could this be simplified to blowback = fixed barrel, non locked and recoil = locked and moving?

Actually most auto pistols are commonly known as delayed blowback meaning there is a mechanical design to keep the breech locked until pressures go down. Some of those designs are link/tilt, tilt/block, rotating barrel, then you have the kidney shape locking lug such as the one EAA uses on their Witness series of pistols. There are also gas retarded and so on. Ask me which one is better? I will probably go with the 1911's link/tilt design because I just love 1911s.

[9mmepiphany]

Thanks for the responses. I guess what is kind of confusing is that in common terms, BOTH are acting on the force of recoil - no?
So could this be simplified to blowback = fixed barrel, non locked and recoil = locked and moving?

the recoil operated action is already shortened/simplified from it's formal name, the short recoil operated, tilting barrel action and the recoil operated roller-delayed action

[Aim2Shoot]

FWIW, here is a video. The first 10 minutes contains a description of BB vs recoil pistols using the 1911 as an example of the recoil type. I learned a little watching this video. The last 4 minutes or so is a rant about a different topic.

http://www.youtube.com/watch?v=mz5E9k6epTE