Semi-auto pistol with locking action?

S

Skans

New member
Has any manufacturer ever made or designed a semi-auto handgun where the action can be locked to prevent it from cycling upon firing a shot. Basically, making the handgun a select-fire semi-auto and single-shot. I would expect that such a design would be for use with a silencer and/or possibly to squeeze out some additional accuracy.

I have not heard of such a thing, but wanted to know if more knowledgeable people have.
 
Skans said:
Has any manufacturer ever made or designed a semi-auto handgun where the action can be locked to prevent it from cycling upon firing a shot. Basically, making the handgun a select-fire semi-auto and single-shot. I would expect that such a design would be for use with a silencer and/or possibly to squeeze out some additional accuracy.
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I know from your prior participation here and elsewhere, that you're not a beginner when discussing firearms issues and function...

I ask the following very seriously -- assuming you're addressing something I don't understand: how would a control on the gun which limits the number of rounds fired enhance accuracy -- or facilitate/improve functionality with a silencer?

As I understand it -- all other things being properly designed and made -- accuracy/precision is a function of the gun's ability to consistently lockup with each shot, so that barrel and sights stay aligned for aimed fire.

Seems as though the ability to limit the gun to one shot doesn't really have much to do with accuracy or silencer function, and could create as many problems as it might resolve -- especially if it's done by a switch that can be inadvertently flipped or flipped earlier and forgotten. If I've got it right -- perhaps I don't -- that would explain why you haven't heard of such a firearm feature.

Maybe there's something more to your question that I'm missing? (While I don't own a silencer or suppressor, I have fired guns using them, and I think I understand how they work. Maybe I don't...)
 
Re: the Hush Puppy.

The reason for a single shot function (and, more importantly, no cycling) was to stop the relatively loud sound of the slide slamming back and forward; it apparently had nothing to do with accuracy

If a second shot was needed (and the shooter still had a chance to take it), he could cycle the slide manually -- and that could be done much more slowly and, in effect, silently.

Thanks for the link! It was very interesting.
 
Smith had a cpl designs to lock the slide for suppressor use. Some guys have modified Ruger Mk's to hold the bolt closed as well

Walt,
There are 3 causes of noise when a gun is fired
1. The blast from the escaping gases
2. Bullet flight noise
3. Action noise from the firearm cycling.

The first is reduced by adding a silencer to the firearm. Thus reducing the blast that escapes into the environment

The second is reduced by the use of Subsonic ammo, thus reducing the sonic crack

The third is reduced by using a firearm that does not have any action noise. Bolt actions are quietier then AR's when suppressed, all other things being equal.

You can further reduce noise by fine tuning ammo specifically for single shot use if you dont HAVE to run the action. In 300 Blackout, my AR loads (the must function the gun) are louder then my Boltgun loads. Same projectile, same speed...different powder, less gas.
 
Chuck, that was an interesting read! I have never seen this before. I knew I couldn't have been the first to ever think of this (although part of me wishes I was), but I've never read about it anywhere. The article states "The frame was modified with a slide-lock that would keep the top end of the pistol securely closed when firing. This feature turned the pistol into a single-shot weapon but eliminated the “click-clack” sound of the slide cycling when the gun was fired."

I'm surprised that with all of the suppressors being sold, no one has thought to modify a suppressor-dedicated pistol to mimic the old S&W Mk 22 referenced in the article.

Walt, to answer your question, I would think accuracy may also be improved by eliminating any movement of the locked action. I know the counter to this line of thought is that the action is locked, and by the time the slide begins to cycle, the bullet is past the muzzle....or just about. However, I think the Thompson contender pistols (single-shot) are known for being more accurate than non-fixed barrel semi-autos.

In any event, I sure would like to see an up close picture of that Mk 22 switch mechanism. I would think that such a switch could be easily incorporated into a Ruger MK II, since there is considerably less force on the bolt.

Anyway, if you want bragging rights to the quietest gun, the suppressor is only a part of the equation. The addition of a simple switch to lock the slide/bolt seems to complete the rest of the equation. Would such a modification be regulated by BATFE? I don't see why it would be under existing laws.
 
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In theory, wouldn't lockup help

This may just be splitting hairs. And I may be wrong :) so correct me if I am.

My understanding of the theory is, if recoil impulse occurs while the bullet is still in the barrel, parts of a semi-auto are still moving. Granted, the pistol is timed so the barrel is still *unlocking* while the bullet exits - but this unlocking does mean movement. The barrel drops as the locking lugs start to disengage. Accuracy would be better the more consistent the motion during disengagement is - less side to side play, only vertical motion and the same rate of vertical motion every time. Moving parts can move inconsistently and enough tolerance/slack is required for movement which is never as consistent as a solid piece of steel.

We hand fit for a consistent final lockup - and I suppose this usually translates to a tighter fit *near* lockup when the first unlocking movements would occur during firing.

But if you could lock the barrel to the slide and the slide to the frame with a lever with sufficient force and a tight fit, you could eliminate a lot of movement. Like a select fire bolt action of some sort, it could transform all 3 parts into a barrel fixed to a receiver - and since it would be fixed to the frame, you would be holding on to the receiver directly, no stock involved. Still areas like the crown and barrel bushing would need a good fit.

I doubt the S&W mentioned above had a tight lockup like I'm proposing. But I think a convertible single shot has the *potential to increase accuracy. It may not be a visible difference at practical combat rage, but in theory a pistol could be made to be as accurate mechanically as a bolt action rifle. But its just not practical.
 
Accuracy of semi autos is limited by the fact that the barrel moves in relation to the sights...

Between shots...

Properly designed semis, will have little movement until the bullet has left the barrel.

And while the real world can see some movement of the slide before the bullet exits the barrel... This has less effective on accuracy than the fact the action cycles at all. (for a properly designed and functioning pistol) So long as the barrel isn't unlocking before the bullet leaves the barrel.


When the action cycles, the barrel does not lock up exactly the same every time. There is some minor variations in the various part's positions. The better made the pistol the less variations. This variation leads to shifting points of impact in relation to point of aim.

As soon as you hand cycled a pistol designed to lock up such as the above referenced pistol... You have induced some randomness that will affect the next shot.


So despite the action being locked up, accuracy will not improve. As there will be shot to shot variations, and you can not predict them.

You can only know your accuracy potential at the various ranges with practice with that pistol, and this requires practice/training. You will know when a shot is feasible for you to take, or if you need to get closer to the target.
 
Anyone who has ever fired a suppressed STEN or M3 SMG knows very well that the noise made by the bolt slap is (or seems to be) almost as loud as the firing itself. In fact the STEN's that were actually used by the British were wrapped with sound deadening material to keep down the noise. Suppressed Ruger .22's have the same problem, and I would assume any auto pistol would have some mechanical noise in its operation.

Contrary to some ideas, including Maxim's, suppressors have rarely been used in combat; combat itself being a rather noisy affair (not as much as a teen dance, though) and silencing one shot is not worth the trouble. The situation in VN was unique, since the suppressor was to keep the shooter from being deafened by the noise of his own gun in the tunnel, not to conceal him from the enemy.

Jim
 
SKANS said:
Walt, to answer your question, I would think accuracy may also be improved by eliminating any movement of the locked action. I know the counter to this line of thought is that the action is locked, and by the time the slide begins to cycle, the bullet is past the muzzle....or just about. However, I think the Thompson contender pistols (single-shot) are known for being more accurate than non-fixed barrel semi-autos.
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Perhaps, but I'm skeptical about a locked slide contributing to better accuracy. I address this in the indented area, below.

With a .45, the bullet has exited the G.I. barrel by the time the barrel has moved about 1/10th of an inch, and I would expect a 9mm to be about the same (or less), with a 9mm or .40. (That said, I've NEVER seen the bullet/barrel/slide relationship photographed or explained for anything but a .45. If anyone knows of one, please share a link!) Barrel length or load and bullet weight may play a role here, too -- but much of this is like "magic" or physics (same difference) to me.

In a gun that cycles, the bullet is about to leave (or has left) the barrel before the barrel has moved much at all. The SLIDE has moved a bit more, but until the barrel starts to unlock from the slide -- which arguably comes later, after the bullet has left the barrel , any rise in the subsequent point of impact due to the rear of the barrel dropping as the slide and barrel separate is not likely to be great.

Consistent fit (barrel/slide (and, i.e., sight) will still be critical even with a locked slide gun, as the gun still has be be loaded. If the barrel/slide fit isn't precise enough to allow very consistent lockup, loading a single round will have much the same effect on barrel/sight alignment as cycling one that isn't locked for the first shot.​

Using a locked slide removes a very small potential for error, but doesn't let the gun perform like a FIXED BARREL gun (ala Thompson Contender.) Cycling it to load it changes the equation.

The biggest difference between a locked slide and one not locked, it seems to me, might be noise. But, maybe I misunderstand something important -- it won't be the first time. If so, I've already learned something new from this discussion, maybe I'll learn some more.
 
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I'd argue that the Semmerling is a manually-operated magazine-fed single-shot, and is thus different than what Skans asked about, since it by definition won't function in semi-auto mode.

The Fiala .22 pistol was similar in concept but with a more conventional layout; AFAIK the Fiala wouldn't function in semi-auto mode either. The basic Fiala design was later converted to semi-auto after Fiala went bankrupt and Hartford Arms was formed to take over their gunmaking operation, but AFAIK Hartford did away with the single-shot feature, so the redesigned pistol wasn't "convertible" either, so to speak.

(Hartford is best known as the predecessor to High Standard; IIRC HS was originally a toolmaker, but they purchased the assets of Hartford Arms at a bankruptcy liquidation sale to obtain their machine tools, and somewhat inadvertently got into the pistol business by assembling Hartford pistols from leftover spare parts.)
 
A point of order:

There are other recoil operated semi autos than the common tilt barrel system. Guns where the barrel NEVER moves in relation to the sights. I own a couple of them. So, when you say "automatics", you should be a bit more clear, and specify tilt barrel (Browning link or cam, or etc) when that is what you are talking about.

And speaking of that system, the barrel does not move, in relation to the sights (& slide) until well after the bullet is gone. Both the barrel and slide move back together for a distance, THEN the barrel is stopped and tilted (to unlock from the slide) while the slide continues back.

As to a semi auto with a "lock shut" feature, the only one I know of was written about in Shooting Times (IIRC), back in the 70s. An assassin's weapon, captured in Viet Nam, Integral suppressor, and a switch to hold it shut (for maximum reduction of noise) if desired.

It was either a completely hand built, or a combloc pistol rebuilt, I cannot now remember, but it was rather crude looking, I remember that.

I'd argue that the Semmerling is a manually-operated magazine-fed single-shot
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We call that a repeater. :D:rolleyes:

I do agree, its not a semi auto.;)
 
There are other recoil operated semi autos than the common tilt barrel system. Guns where the barrel NEVER moves in relation to the sights. I own a couple of them. So, when you say "automatics", you should be a bit more clear, and specify tilt barrel (Browning link or cam, or etc) when that is what you are talking about.
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They DO move in relation to the sights, just not as much, and hardly at all on the vertical plane. Keeping precise (consistent) lockup is still an issue, but arguably easier to obtain. (That a good bit of work is required to achieve this necessarily consistent lockup is evidenced by the US Army's Marksmanship Unit's skilled gunsmiths, who spend a lot of time and effort accurizing the USAMU Shooting Team Beretta M9s (and other weapons...)

While the standard issue M9s are good service pistols, they're not close to Bullseye pistol accuracy, and seemingly no better than similar Glocks or SIGs, or H&Ks. Interestingly, Wilson Combat is now offering similarly upgraded Berettas -- so Wilson, at least, considers them worth the effort.

I wonder how those M9/92s ( service) pistols stack up against a SIG M49 (P-210-2?). The P-210-6 I had, years ago, would do a sub-2" group of 5 shots at 50 meters (roughly 55 yards) from a rest. That SIG line used the theoretically less accurate Browning Locked Breech short recoil system which is based on a tilting barrel.

As to a semi auto with a "lock shut" feature, the only one I know of was written about in Shooting Times (IIRC), back in the 70s. An assassin's weapon, captured in Viet Nam, Integral suppressor, and a switch to hold it shut (for maximum reduction of noise) if desired.
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There's a link the third response in this discussion tells us about (and shows) a weapon used by US Special Ops troops in the Vietnam War. It was a silenced S&W Model 39, with a slide that could be locked shut to avoid the noise of the slide opening and closing. When shooting from cover, close to the target, slide noise might reveal the shooter's position.
 
There is another facet of sound in a semi-auto.
Part of the sound from the powder burn escapes through the REAR of the chamber, after the slide or bolt ejects the case.

A locked, or "sealed" breech eliminates that.
Denis
 
They DO move in relation to the sights, just not as much, and hardly at all on the vertical plane.
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The Berettas? ok. The P.38? ok.

now here's a couple that don't move in relation to the sights..





My point is that there are other systems and if you aren't including them in blanket statements about "autopistols", you aren't being fully accurate.
 
I had thought the High Standard suppressed rimfire pistols that were actually issued (in a clandestine fashion...?) included a slide-lock for exactly the reason the OP asked about?

Also, and I'm kind of surprised that 44 AMP didn't suggest this one...
Although not a design feature as such that it was meant to work in this manner, it seems to me that a Wildey semi-auto Magnum pistol SHOULD be able to pull this off due to it's adjustable gas system. This assuming you had some loads cooked up that were not full-boat AND you opened up the gas system to it's full ability...

Of course, I've never even handled a Wildey and IIRC, 44 AMP has one, so he would be able to tell us if this is even possible. I had heard you could pull this off with the regulator on an FAL rifle... but once again, I have no experience with them either.

I have, with a firm hand, held the bolt of my Ruger Mark II closed while firing a shot. It is NOT great for markmanship... but it is not difficult to do it. The pistol certainly doesn't seem to care one way or another.

To the subject at hand -- I've often thought it might be a somewhat desirable and oddball idea... a manually operated repeater, like the Semmerling. Now the Semmerling worked the way it did for the select purpose of it's extremely compact size (for the time) and not because it might be a neat sales feature. But in a world where folks -LOVE- rifles that operate with bolts and levers, and single action revolvers where cocking is required for each shot and unloading/reloading is a "coffee break" length of time & work, I can't see why a manually operated and magazine-fed repeating handgun would seem so outrageous.

Heh. If you have a Jennings, Bryco or Davis... ya almost already own one. ;)
 
Run a search on the Mk22 Mod 0 Hush Puppy, a modified S&W Model 39 used in Viet Nam by SEALs.
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Interesting weapon.

I realize the pistol was used on humans as well as dogs, but if the weapon were restricted to dogs only, would it be okay under the Hague Convention to use JHPs? Or, is the simple possession of JHPs on a battlefield void of illegal combatants a violation of international law?
 
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