Linear compensator on a handgun with a tilting barrel

[sorvanetzsorv]

I am curious about a possibility of using a linear compensator on a service-sized handgun with a tilting barrel (such as, say Glock 17 or Sig P226).

The rationale is the redirection of the report of the gunshot downrange and away from the shooter (as well as the possible beneficial change of the flash signature with a fireball to a more cylindrical shape). This may be of use in those locales where sound suppressors are illegal.

I understand that the effect is likely to be small, but even a difference of several db may be noticeable (coupled with the use of subsonic ammo).

There are a couple of potential problems associated with this attempt. Let's consider for example the KVP LINEAR COMP in 9mm:

https://www.kawvalleyprecision.com/KVP-Linear-Compensator-p/kvp-linear-blk.htm

It weighs 2.9 oz - would attaching it create an issue with reliable cycling of a handgun with a tilting barrel?

Another conceivable issue is something similar to a baffle strike - I do not know the exact diameter of the exit opening, but most likely it's no more than 10mm. Is there any chance the bullet can strike it (after traveling about 2" inside the comp)?

Thanks!

[James K]

I would have to assume that the manufacturer makes the hole big enough for the caliber of the rifle the comp is made for (.22 or .30). As to the effect of the weight on the barrel and on functioning, I suggest calling the manufacturer. I know from experience that some suppressors can and do add enough to the mass of the recoiling barrel that they interfere with functioning, but that gadget looks small and light enough that it probably will be OK. But I do note that there is no mention of its use on a gun with a recoiling barrel, only on gas operated guns.

Jim

[sorvanetzsorv]

You can see in the drop-down list at the link I posted above, that there are two 9mm versions of this comp - with 1/2x28 and 1/2x36 threads. They are typically used on PCCs like AR9 or Sub2K - all those have fixed barrels. So, the opening is large enough for the 9mm bullets. The possible problems are due to the tilting of the barrel - the handgun may not cycle properly because of the extra 2.9 oz weight at the end of the barrel, and the tilting of the barrel can potentially result in the bullet striking the opening of the comp. It's most likely that handgun manufacturers will not comment on this unorthodox use case due to liability issues.

[dakota.potts]

I guess you'd need to do some type of study or research on the timing and unlocking cycle of whatever handgun you're working with. If the recoil operation doesn't start until after the bullet has left the barrel, I don't see how it could affect anything as far as baffle strikes. Guns with these systems are commonly suppressed, which has a much longer travel without a baffle strike, so I'd think (guessing) that you would be OK there. I've seen Glocks and other tilting barrel handguns with various compensators and they seem to work OK.

I doubt 2.9 oz would affect the cycling enough to be an issue, especially if the gun in question already has a healthy ejection pattern.

[Jim Watson]

If the doodad is screwed on the barrel, then it tilts as the barrel locks and unlocks and alignment is maintained.

Whether the gun will run with it I cannot say.
Silencers for recoil operated guns typically have "Nielsen devices" to amplify the recoil. I know a guy who tried to adapt his rifle silencer to a pistol and it did not work. I know another guy who tried something as small as a "sight tracker" and had to do a lot of tinkering.

On the other hand, a compensated racegun does fine.

[sorvanetzsorv]

The reason a strike is conceivable is because at the precise moment the bullet exits the barrel, the slide and the barrel are still moving back together. If the unlocking happens at this very moment and the barrel starts tilting, then the bullet will be traveling strait for about 2" inside the comp, but at the same time the barrel will be tilting together with the comp. Of course, the bullet is moving much faster than the barrel, but if the exit opening of the comp is very tight (close to 9mm), it seems to me there is a strike possibility. Is there any flaw in this reasoning?

[ShootistPRS]

As long as the bullet is in the barrel it is following the barrels movement. Under recoil that movement is an arc and neither the barrel nor the bullet are moving in a straight line but once the bullet exits the barrel it will take on a ballistic arc while moving away from the muzzle and following the three dimensional path it was on at exit.

[James K]

I think I see what sorvanetzsorv is saying*, but that problem should exist for any suppressor mounted on a tilting barrel pistol, and most are a lot longer than the gadget under discussion. All I can say is that I have never seen any discussion of a problem with a suppressor on a BHP, 1911, or the like.

Now if the gun is something like the Ruger LCP with a barrel that tilts at a steep angle, things might be different. Anyway, the discussion is irrelevant in this case since the comp under discussion seems to have not been made for anything but a gas-operated rifle or handgun, where the barrel is fixed.

Jim

*If I understand, the "problem" is that the barrel and comp are fixed together, so the bullet will exit the barrel in a straight line, but the barrel-comp assembly can move while the bullet is inside the comp, changing the direction of the bullet relative to the line of the barrel-comp exit.

JK

[JohnKSa]

Guns with these systems are commonly suppressed, which has a much longer travel without a baffle strike, so I'd think (guessing) that you would be OK there.
...that problem should exist for any suppressor mounted on a tilting barrel pistol, and most are a lot longer than the gadget under discussion. That's a good answer to the bullet strike issue.

Hard to say what's going to happen with function. 2.9oz isn't much, but as a percentage of the combined slide/barrel mass it's not trivial either. I wouldn't worry terribly much about this. I would think that one could find a loading (either factory or handloaded) that would work reliably. The slide velocity is proportional to the muzzle momentum and that can be varied somewhat by selecting a different loading.

[Walt Sherrill]

As long as the bullet is in the barrel it is following the barrels movement. Under recoil that movement is an arc and neither the barrel nor the bullet are moving in a straight line but once the bullet exits the barrel it will take on a ballistic arc while moving away from the muzzle and following the three dimensional path it was on at exit.

While the recoil arc begins immediately with a revolver, there is no recoil arc with a tilting barrel semi-auto until the slide and the barrel have begun to unlock. Until the unlocking process takes place, all key components ARE moving horizontally in a straight line -- with the barrel and slide moving to the rear, and the bullet moving in the opposite direction. And the bullet is gone from an unsuppressed or uncompenstated barrel before the unlocking process has begun or the recoil arc can begin.

Does the bullet leave a compensator or suppressor before a tilting barrel system has begun to tilt? I've been unable to find any YouTube videos that address this quesiton, or show how a mounted suppressor (which seems like a more critical issue) affects point of impact, but it appears that suppressors work equally well on tilting and rotating barrel recoil systems, when they are properly fitted and matched to the caliber of the weapon. And they don't seem to self-destruct.

A .45 round will leave the barrel when the slide has moved about 1/10th of an inch, And while the total time elapsed can be different with other calibers and bullet velocities, the relationship between the barrel, slide, and bullet (how they interact) remains the same; they just do it uniformly more or less quickly depending on the velocity and caliber and weight of the bullet.

As the bullet leaves the barrel and enters an attached compensator or suppressor, the bullet is moving much more rapidly as it exits the barrel than it was getting to that point! -- because the bullet had to be accelerated from a dead start! That might suggest that the bullet is moving much more quickly going forward than the slide is moving to the rear during recoil. That might also suggest that a bullet will have moved past a compensator and be near or beyond the far end of a suppressor before the recoil arc has actually begun.

(Someone better at math than me can probably figure how long it takes a bullet to move an extra six or seven inches at a given pistol round velocity.) I have no way of knowing how fast the slide is moving...

If someone has links to good YouTube videos that address this question, please share them with us.

[ShootistPRS]

Walt,
Since the barrel and slide are retarded by a spring there is recoil as soon as the bullet begins to move. It is lessened but it does exist. The fact that the barrel is above the center of rotation requires the movement be an arc.
I shoot both revolvers and auto-loaders and I can tell you that "felt" recoil can be less in a revolver than in a semi-auto. That happens when the gun is allowed to rotate in the hand rather than using a strong-arm grip to control the recoil. The semi-auto must be held firmly for the action to function properly not so in a revolver.

The physics are different than the feel. All actions have an equal and opposite reaction. Both types of gun have recoil from the time the bullet starts to move. The auto-loader absorbs some of that recoil in the spring but the spring is pushing back on the frame of the gun and the gun is pressing back on your hand.

at 850 fps a bullet moves 10200 inches per second
It will move 1 foot in 0.000098 seconds

[JohnKSa]

Since the barrel and slide are retarded by a spring there is recoil as soon as the bullet begins to move. It is lessened but it does exist. The fact that the barrel is above the center of rotation requires the movement be an arc.There is definitely recoil, but the motion is almost exclusively linear motion of the slide and barrel. This can be easily verified in slow motion video and, for those without such resources, by measuring the bore axis vs. sightline. In a revolver, the boreline and sightline obviously diverge because by the time the bullet leaves the barrel the bore isn't pointing where it was at the beginning of the firing cycle. So it's pretty easy to see that the bore is pointing below the sight line.

But in an autopistol, the boreline and sightline don't show the same disparity because the recoil motion that occurs while the bullet is in the bore induces almost no muzzle lift.

https://thefiringline.com/forums/showpost.php?p=6165790&postcount=38

http://thefiringline.com/forums/attachment.php?attachmentid=88537&d=1364785899

Because of the spring which weakly couples the slide/barrel to the frame there is some muzzle lift, but only a very small amount. The muzzle lift in an autopistol happens primarily after the barrel hits the frame.

[Walt Sherrill]

Since the barrel and slide are retarded by a spring there is recoil as soon as the bullet begins to move. It is lessened but it does exist. The fact that the barrel is above the center of rotation requires the movement be an arc... The physics are different than the feel. All actions have an equal and opposite reaction. Both types of gun have recoil from the time the bullet starts to move. The auto-loader absorbs some of that recoil in the spring but the spring is pushing back on the frame of the gun and the gun is pressing back on your hand.

What equal but opposite action occurs during the first fraction of an inch of slide movement (as the bullet is leaving the barrel) that could cause the barrel to rise? The only forces possible at that point is the slide and barrel moving to the rear and the bullet moving forward. The recoil spring has only been triviailly compressed, but it's being compressed horizontally, too -- straight back by the slide movement. The barrel hasn't even started to unlock yet!

Barrel or slide rise doesn't come until later -- after the rearward movement of the barrel against frame or slide stops has caused the barrel to tilt, and the rearward movement of the slide has moved the gun's center of gravity to the rear.

That all happens, relatively speaking, LONG AFTER the bullet has left the barrel.

There are a number of ultra high-speed videos of short-recoil tilting barrel actions with slides moving and bullets exiting the barrel on YouTube, and there's no barrel rise until after the bullet is gone! Here's a good one -- a MYTHBUSTERS video of a 1911 being fired and videod at 73,000 frames per second. No barrel rise until (relatively speaking) long AFTER the bullet is gone. You can see this at about 10 seconds into the video.

https://www.youtube.com/watch?v=7y9apnbI6GA

Here's another one, shot at only 16,000 frames per second -- but the results are equally obvious. No slide or barrel rise until after the bullet is gone.
https://www.youtube.com/watch?v=ySO0EWIlOKc

at 850 fps a bullet moves 10200 inches per second
It will move 1 foot in 0.000098 seconds

OK. So how long will it take that same bullet to move on through a suppressor or compensator after it's left the barrel? And how far to the rear will the slide move in that same very small fraction of a second? The slide is moving much more slowly.

Let's use your calculation: if the bullet travels 1 foot in 0.000098 seconds it is going to be out of the barrel (and through a compensator or a longer suppressor) before the slide, which is moving much more slowly, has unlocked from the barrel. Yet it's only when that unlocking process has begun, along with the slide's weight shift to the rear takes place from its rearward movement, that you start to see any vertical movement of the slide or barrel.

Watch the videos. I'm sure you can find other videos. The last time I searched I found several, and one with very clear calibration marks on the slide and frame to show the amounts of vertical and horizontal movement of the barrel and slide. I didn't see them this time, but they're probably still out there, somewhere.