Delayed Blowback Operations(Apart From Roller Locking/Kiraly)

[Braith-Wafer]

Does anyone out there know more about other Delayed Blowback operations apart from Roller Locking/Kiraly?

I would like to know about:
Chamber Ring Delayed Blowback
Hesitation Locking (As in the Remington 51)
Blowback Breech Lock

I heard the Schwarzlose MG used a Delayed Blowback Operation that had somthing to do with a reciever.

 

[mete]

Rem 51 is a momentum block system.Benelli M76 pistol was a hesitation lock [toggle system].HK P7 uses gas delay.Schwarzlose MG and pistol used a toggle [?] delay.

 

[Clipper]

There was a MG that used the firing pin shank to pivot lugs into receiver notches as it passed forward to ignite the round. The return spring then pulled the shank back, allowing the lugs to withdraw and disengage...I forget the specific model, but I think it was a German piece.

 

[SDC]

The chamber ring principle wasn't tried too often, mainly because it didn't work very well; the Kimball 30 Carbine pistols used chamber rings, but still didn't slow opening enough to prevent a few slides from breaking completely off the frame during firing. You can also add gas-delayed blowback to the list, such as used in the P7 series; with these, some of the same gas that's pushing the projectile up the barrel is tapped off into a separate chamber, where it's used to retard the opening of the breech.

 

[Jim Watson]

I have owned a Remington 51 - internal moving breechblock. Pretty smart, Mr Pedersen designed the initial movement of the breechblock to be .18", which is the thickness of the solid casehead of a .380. So no danger of case rupture.

I have owned a H&K P7 with gas piston retardation. Slick. I liked that part but could not get along with the funky squeeze cocker unless I abstained from shooting any other gun for a few weeks. Not willing to give up my Colts and Smiths, I sold the P7.

Seecamp uses the Mann chamber ring, which allows the brass to expand and then have to be resized to be extracted. The 1950 High Standard T3 9mm worked that way and was ok as long as it got the ammo its ring was cut for. Different load, harder or softer brass, and it went to hell. Colt tried to fine tune some of the last .38 Special wadcutter Gold Cups with a thread-like chamber cut for the purpose. Better they had made it like Clark converted Supers.

The 1905 Mannlicher pistol had a delay arm in a notch in the bottom of the breechblock. Facing angles were such that the arm cammed down under chamber pressure, no mechanical unlocking required.

Maj Thompson thought the Blish system of inclined lubricated plates briefly sticking together under pressure was enough of a delay for his submachine gun. I don't know for sure about his Autorifle but it might have depended on that, too.

The Pedersen auto rifle had a toggle breech, but unlike Luger the toggles were never lined up straight and had the tendency to come open under pressure, which made it a retarded blowback instead of locked.

One school of thought says the Searle system of a rotating barrel in the Savage pistols was more a delay than a lockup, with only 5 degrees of rotation. There was a French MAB rotating barrel pistol that was delayed blowback although the later and better known PA15 was fully locked.

That's all I can think of at the moment.

 

[Gewehr98]

Which makes me wonder...

About my 1912 Steyr-Hahn, and the rotating barrel within. Definitely more than 5 degrees of rotation, though.

 

[unspellable]

Action?

It has been my experience that there is a lot of confusion out there as to what's which when it comes to the question of a locked breech, blow back, delayed blowback, or retarded blowback.

I have a CZ-52 which has cammed rollers but it is a locked breech recoil operated pistol.

 

[Gabe]

What system did the Mauser C-96 use?

 

[Jim Watson]

Recoil operated locked breech. What some call the "prop-up" system.

 

[unspellable]

C96

The Mauser C96 is a locked breech recoil operated system. It is what I refer to as a reciprocating bolt system, meaning it has a "bolt" as opposed to a slide, which moves back and forth without any other motion. The bolt is locked in battery by a block underneath which cams down in recoil. The Nambu is similar. The Lahti is similar except that the locking block is on top of the bolt rather than under.

A Ruger 22 pistol would be an example of an unlocked blow back operated reciprocating bolt.

 

[Jim K]

I have to disagree on the Benelli 76, as well as the MAB P15 and the Steyr-Hahn.

All are actually locked breech, not delayed blowback. The Benelli is (AFAIK) unique in that it allows a short initial movement of the breechblock to act on the slide, kicking it back and then using its inertia to unlock the breechblock from the frame and continue the cycle. The MAB and Steyr-Hahn (and the Roth-Steyr as well) are locked breech. The barrel is locked to the slide (bolt in the case of the Roth-Steyr) while the barrel turns. The movement allows the pressure to drop before the gun opens. Some will say that the unlocking is taking place while the barrel-breech unit is recoiling, which is true, but is also true of every other locked breech recoil operated pistol I know of, including the M1911, Luger, P.38, M9, etc.

The jury is out to some extent on the Remington 51. It comes very close to a true locked breech, as the breechblock, like the Benelli, is locked until the slide picks it up.

Actually, neither Pedersen (Remington Model 51) or Searle (Savage) designed those actions because there was any real advantage. They had to avoid infringing the Browning patent on a slide combined with the breechblock. It was obvious to everyone that the Colt design was the way to go, but that way was blocked, so other ideas had to be tried. (S&W avoided the slide altogether, as did Davis.)

Jim

 

[Jim Watson]

The breechblock in MY Remington 51 was free to move that .18" before it locked and waited for the slide to pick it up. I just wish the Navy had had time to equip with the Remington 53 .45 with trickle down to the commercial market. Gen Hatcher said it was a good shooting pistol, much nicer than the hard kicking Savage.

The B76 is just peculiar. Probably out of the same design studio as their shotguns.

I would put them both in a separate category, neither quite fully locked nor blowback even delayed. I have heard them called "hesitation" actions.

The MAB PA15 (PA 8 single stack) is a locked breech rotary barrel like Steyr Hahn, Obregon, Colt All American 2000, or Beretta All Italian 8000. (I made up the All Italian part.) Howsomever there was an earlier version MAB, the Type R, that had none of the locked travel of the other rotating barrel pistols. I agree with Jan Stevenson that it is delayed blowback.

 

[Gabe]

Ah, thanks for the replies, Jim and Unspellable.

 

[mec]

AMT did something with the ruger mk I look-alike .22 AutoMag. It was called a "plenum" chamber. Had a series of holes drilled into the chamber that worked something like the ring delay. cases emerged with little dimples all over them.

 

[Jim Watson]

I think the .22 Automag was the opposite of retarded blowback. The plenum around the chamber was pressurized from ports right in front of the chamber as the bullet entered the bore. That bled a little gas into the chamber around the case, floating the long, skinny, thin rimfire brass out without pulling it in two. Similar principle to H&K chamber flutes.

 

[Badger Arms]

The Remington 51 is definitely a LOCKED breech firearm. It is blowback actuated, but the breech is indeed locked. It operates in virtually the same manner as modern gas-operated firearms, however the piston is the case and the barrel is the cylinder. Quite simple. The Benelli is just weird though. Ross Rudd made a similar pistol.