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Old September 8, 2018, 12:42 AM   #26
HisSoldier
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The Benelli lock design (inertial, that being, as the frame/barrel is recoiling the slide is resisting said recoil, and that inertia force presses the locking flap down into it's locked position until the slide "Catches up".) is very interesting and works independent of the barrel or frame, the entire locking design is at the rear occupying a very small space.

That design, the Benelli Inertial lock, is truly beautiful, one of those ideas that makes one feel like "I wish I'd thought that one up".

Their shotgun inertial locks work on a slightly different concept, it still uses inertial forces to time the unlocking but I seem to remember it being rotary or something, but they seem to have had the principle in mind for a while at least.
The only downside to the B series pistols is the use of stamped steel shells welded together for the frame, but at least they did it in such a way that it doesn't look cheap like so many such cheap processes look. The .30 Parabellum pistol is convertible to 9MM with just a barrel change, though it's a bit involved.
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Old September 8, 2018, 01:29 AM   #27
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Very nice!

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Old September 8, 2018, 05:47 AM   #28
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Quote:
The Benelli lock design (inertial, that being, as the frame/barrel is recoiling the slide is resisting said recoil, and that inertia force presses the locking flap down into it's locked position until the slide "Catches up".) is very interesting and works independent of the barrel or frame, the entire locking design is at the rear occupying a very small space.

That design, the Benelli Inertial lock, is truly beautiful, one of those ideas that makes one feel like "I wish I'd thought that one up".

Their shotgun inertial locks work on a slightly different concept, it still uses inertial forces to time the unlocking but I seem to remember it being rotary or something, but they seem to have had the principle in mind for a while at least.
The only downside to the B series pistols is the use of stamped steel shells welded together for the frame, but at least they did it in such a way that it doesn't look cheap like so many such cheap processes look. The .30 Parabellum pistol is convertible to 9MM with just a barrel change, though it's a bit involved.
Yeah they make it sound fancy and it’s certainly a cool design. In reality nothing really “locks”. The lever just delays the blowback a bit.

And, yes, the frame is a shell much like a Ruger Mark Series pistol. Frame aside, the Benellis are high quality handguns.
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Old September 9, 2018, 12:37 AM   #29
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Bac123,
There is a question I've had many times about "Locked breech" vs "Delayed blowback", but only with some designs. The Benelli is one of them.

I know they call delayed blowback, but as long as that flap in the Benelli action is pushing the bolt down into the recces, it's locked. It's locked based upon a given amount of pressure vectored down based on certain reactive ballistic inertia, so that if the velocity is raised the lock up remains until the pressure is relieved. When the breech opens there is not enough pressure remaining from the case pushing back to cycle the slide, it's the velocity of the slide before opening that cycles the slide, just exactly as it is in the 1911.

Anything that keeps the breech closed until the bullet is out of the barrel and the pressure has dropped does the same thing, and that time allows higher pressures to be used by time limiting the remaining pressure that the withdrawing case walls have to withstand without support.

This is just me perhaps, but if a mechanism keeps the breech closed until that time what's the difference? If the breech cannot open until the pressure is low enough it's locked in my opinion.

There is no "Blowback" forces involved in cycling either. The cartridge case blowing the breech back acting like a piston (as in a true blowback) does not exist in this design, as by the time the breech begins to open there is little pressure left. In that regard it is the same as a 1911, both use the inertia of the recoiling masses of the slide to extract the empty case and cycle the action.

The only way I can justify looking at a true locked breech action differently is in that increasing pressure without allowing the slide to move back on the frame would eventually have to shear the locking ribs to open. A blowback will open even with the slide clamped in a vise, and a Benelli would too as long as the gun is not allowed to recoil.

If it recoils it is locked.
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Old September 9, 2018, 12:44 AM   #30
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Correction to the above, "If it recoils it is locked.", is only true as long as the recoil of a Benelli pistol is accelerating, as when the bullet is still accelerating down the bore. Once it leaves the bore recoil acceleration stops and the bolt is unlocked.
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Old September 9, 2018, 07:13 AM   #31
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Bac123,
There is a question I've had many times about "Locked breech" vs "Delayed blowback", but only with some designs. The Benelli is one of them.

I know they call delayed blowback, but as long as that flap in the Benelli action is pushing the bolt down into the recces, it's locked. It's locked based upon a given amount of pressure vectored down based on certain reactive ballistic inertia, so that if the velocity is raised the lock up remains until the pressure is relieved. When the breech opens there is not enough pressure remaining from the case pushing back to cycle the slide, it's the velocity of the slide before opening that cycles the slide, just exactly as it is in the 1911.

Anything that keeps the breech closed until the bullet is out of the barrel and the pressure has dropped does the same thing, and that time allows higher pressures to be used by time limiting the remaining pressure that the withdrawing case walls have to withstand without support.

This is just me perhaps, but if a mechanism keeps the breech closed until that time what's the difference? If the breech cannot open until the pressure is low enough it's locked in my opinion.

There is no "Blowback" forces involved in cycling either. The cartridge case blowing the breech back acting like a piston (as in a true blowback) does not exist in this design, as by the time the breech begins to open there is little pressure left. In that regard it is the same as a 1911, both use the inertia of the recoiling masses of the slide to extract the empty case and cycle the action.

The only way I can justify looking at a true locked breech action differently is in that increasing pressure without allowing the slide to move back on the frame would eventually have to shear the locking ribs to open. A blowback will open even with the slide clamped in a vise, and a Benelli would too as long as the gun is not allowed to recoil.

If it recoils it is locked.
I hear what you're saying with the lever during the blowback process. Its still a blowback. When you manually pull the slide back, the slide and barrel immediately separate. There is no locking point at the start, which is totally different from a locked breech. That was my point.

Several delay designs essentially "lock up" during recoil. The Korriphila HSP has a similar effect with its roller, but its still a blowback gun.
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Old September 11, 2018, 03:28 AM   #32
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I hear what you're saying with the lever during the blowback process. Its still a blowback.
Not if the term blowback means that the case moving rearward while the bullet is accelerating down the bore, which case movement is acting as a piston to push the slide back for cycling. The breech in a Benelli is closed tight until rearward acceleration stops, beyond which point the extractor pulls the case out. In a true blow back an extractor isn't even needed theoretically. In the benelli or the 1911 an extractor is mandatory because there isn't enough pressure in the breech left to push the case out after opening. (In theory, but in reality there is some pressure still unvented)

A "Case" in point, a .22 Ruger pistol when it fires, as the bullet is traveling down the bore the bolt is opening because the case is pushing it back like a piston. The pistol relies on the reduced power of it's cartridge (lower pressure) to keep from blowing the sides out of that moving case.
The 1911's slide movement in recoil acts to unlock the breech after the bullet has left, but in theory using a long enough barrel with slow enough powder could open the breech while lots of pressure remains. The Benelli on the other hand cannot unlock until bullet acceleration has ceased, so in that imaginary situation it is an even more secure lock than the 1911.
You could call it a hesitation lock, but it's not a blowback.
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Last edited by HisSoldier; September 12, 2018 at 03:00 AM.
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Old September 11, 2018, 07:21 AM   #33
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Not if the term blowback means that the case moving rearward while the bullet is accelerating down the bore, which case movement is acting as a piston to push the slide back for cycling. The breech in a Benelli is closed tight until rearward aceleration stops, beyong which point the extractor pulls the case out. In a true blow back an extractor isn't even needed theoretically. In the benelli or the 1911 an extractor is mandatory because there isn't enough pressure in the breech left to push the case out after opening. (In theory, but in reality there is some pressure still unvented)

A "Case" in point, a .22 Ruger pistol when it fires, as the bullet is traveling down the bore the bolt is opening because the case is pushing it back like a piston. The pistol relies on the reduced power of it's cartridge (lower pressure) to keep from blowing the sides out of that moving case.
The 1911's slide movement in recoil acts to unlock the breech after the bullet has left, but in theory using a long enough barrel with slow enough powder could open the breech while lots of pressure remains. The Benelli on the other hand cannot unlock until bullet acceleration has ceased, so in that imaginary situation it is an even more secure lock than the 1911.
You could call it a hesitation lock, but it's not a blowback.
I guess people can call it what they want. To me, its a blowback due to no initial locking mechcanism that works whether the gun is fired or not. Its the blowback action that locks in the lever in the first place.

Every publication and book I've read or video I've watched describes the B76 as a delayed blowback pistol. Even Wiki does. In fact, the B77 and the 32 Long MP3S work as straight blowbacks without the lever.

I realize what you're saying, but to me a locked breech is readily apparent the moment you pull the slide back, whether it's a typical Browning link or cam design, a Walther designed falling block, a CZ roller lock etc. None of these need to be fired for a blowback force to lock anything into place. Granted the Benelli design is cool and unique, but its most definitely a blowback in my book. I'm certainly not alone in saying that.

Its all cool though and I appreciate your insight.
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Old September 11, 2018, 08:08 AM   #34
Jim Watson
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I think it was Donald Simmons who tested for lockup by putting a cleaning rod down the barrel against the breechface, holding the gun by the butt, and pushing. A locked breech will not open, blowback will. Delayed blowback will. I think he said the Benelli would open that way.
You have the collection, let us know which moves and which doesn't.
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Old September 11, 2018, 12:33 PM   #35
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I think it was Donald Simmons who tested for lockup by putting a cleaning rod down the barrel against the breechface, holding the gun by the butt, and pushing. A locked breech will not open, blowback will. Delayed blowback will. I think he said the Benelli would open that way.
You have the collection, let us know which moves and which doesn't.
It opens fine. I just tried it with my B76.

Honestly, I think a locked breech will also though.
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Old September 11, 2018, 03:16 PM   #36
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Tried it on a 1911, went right back. So much for that theory.
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Old September 12, 2018, 03:34 AM   #37
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I think it was Donald Simmons who tested for lockup by putting a cleaning rod down the barrel against the breechface, holding the gun by the butt, and pushing.
You my be referring to the youtube video I saw where the guy "Tested" 4 different action types. His holding the grip and pushing a rod down the bore left out the real life part that the Benelli uses to lock the breech shut. The slide has to be exerting pressure in the pivoting link to hold the breech block down into it's locking surface, without having a third hand pulling the slide forward it proves nothing.
And yes bac1023, blowback always means to me that the cartridge case is acting as a piston to push the breech back while the bullet is traveling down the bore, which does not happen with the inertial lock. All pistols except a few gas operated ones rely on the gun blowing back, so by your definition they are all blowbacks. If we can agree that a Colt 1908 .380 uses the cartridge case pushing (Moving like a piston) back the breech to cycle the slide then we'll be able to see why a Benelli isn't a blowback anymore than a 1911 is.
In a Remington action video I saw a commentator suggested that the short rearward movement of the case to the rear, which then stops the breech momentarily, acts like a short stroke tappet ala M1 Carbine, but that short case movement is pure blowback! The video was trying to say the 51 was better locked than most other locked breech pistols, but in fact the partially extended case is unsupported much more than any locked breech gun.
As far as what Wiki says I couldn't care less, but here's what I read there; "First manufactured in 1976, the Benelli B76 is a locked-breech, fixed-barrel pistol, that works thanks to a unique "inertia lock" system, as explained in U.S. Patent 3,893,369. In this system, the gun has a bolt provided with ribs extending transversely to the bolt axis and adapted to engage in and disengage from corresponding mating grooves in the receiver, and a locking lever that links the bolt with the slide which acts as a bolt carrier. Upon firing, while the pistol recoils in the hand of the shooter, the inertia of the slide makes it maintain its position relative to the receiver, constraining the bolt ribs' motion in the corresponding grooves via the locking lever, and so keeping the breech positively locked. As soon as the recoil movement of the pistol in the hand of the shooter slows down." (https://en.wikipedia.org/wiki/Benelli_B76)

Benelli calls it an hesitation lock I think.
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Old September 12, 2018, 05:34 AM   #38
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Wiki descriptions are always off. Look at the spec they list. They at least get that from credible sources. It’s listed as lever delayed blowback, just like every publication I own that talks about the design.

You can call it whatever you want. To me, it’s a blowback. There is no locking that isn’t initiated during the firing process. To me a locked breech locks together the slide and barrel whether the gun is fired or not. Pulling back the slide and the two are together for a short distance.

The B76 is a fixed barrel delayed blowback.

http://modernfirearms.net/en/handgun...nelli-b76-eng/

Last edited by bac1023; September 12, 2018 at 07:47 AM.
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Old September 12, 2018, 07:36 AM   #39
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While I'm at it, here is a sampling of some other delayed 9mm and 45ACP blowbacks from my collection.

AJ Ordnance Thomas (lever)
HK P7M13 (gas)
Astra 600 - actually this a straight blowback. Stuck it in the pic by mistake
Steyr GB (gas)
HK P9S (roller)
Korriphila HSP (roller)
MAB PA-15 (rotating barrel)



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Old September 12, 2018, 10:01 PM   #40
Jim Watson
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in fact the partially extended case is unsupported much more than any locked breech gun.
In the PA 51, the case is "partially extended" only for the thickness of the .380 case head, so there is no unsupported sidewall.
See also Tanfoglio FAR.
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