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Old 11-12-2017, 06:04 AM   #1
linny
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Default Threading Revolver Barrels

My friend and I are going back and forth on this and wanted to see what “learned” men had to say.

I would like to thread a .38 Special revolver of some sort to take subsonic loads, however my friend who is a revolver guy argues that the forcing cone has too much slop which will become an avenue for dangerous amounts of back pressure when fired suppressed.

I also look to the Nagant revolver which seems to work just fine with a can.


So I ask you out there, what factors should I take into respect before removing the barrel and singnle point thread some 1/2-36 threads?

-Linny
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Old 11-12-2017, 06:20 AM   #2
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The cylinder on the Nagant moves forward to make a seal between the barrel and cylinder when firing.
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Old 11-12-2017, 06:53 AM   #3
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Barrel/cylinder gap will most likely vent any excessive pressure and render suppression moot in the process. If you shot it suppressed enough, accelerated gas cutting on the forcing cone, cylinder face and frame might become an issue too. Might be a fun experiment but I think you'll probably be disappointed with the results unless you used a Nagant.


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Old 11-12-2017, 04:40 PM   #4
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Just about all .38 Special loads are subsonic.

If you want to suppress a revolver, get a Freedom Arms. They cylinder gap is tiny.

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Old 11-12-2017, 05:02 PM   #5
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What is your point in adding a suppresser to a revolver? Not trying to be scenically but like others have stated the gap between the Cylinder and the barrel will keep you from silencing it much. If you just want quieter, you would probably be better off with some really light loads. If you reload, then it's not much of a problem but if you don't then that's a different story.
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Old 11-12-2017, 10:43 PM   #6
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Quote:
Originally Posted by linny View Post
My friend and I are going back and forth on this and wanted to see what “learned” men had to say.

I would like to thread a .38 Special revolver of some sort to take subsonic loads, however my friend who is a revolver guy argues that the forcing cone has too much slop which will become an avenue for dangerous amounts of back pressure when fired suppressed.

I also look to the Nagant revolver which seems to work just fine with a can.


So I ask you out there, what factors should I take into respect before removing the barrel and singnle point thread some 1/2-36 threads?

-Linny
Trying to suppress a revolver is a waste of time, as stated, a large portion of the sound escapes from the cylinder gap, and if you put a suppressor on the barrel, the back pressure will increase, so that sound level will go up, I did it for a customer who wouldn't believe me, and then demonstrated it to him with a sound meter suppressed and unsuppressed.

The sound level the meter registered went up 1 dB suppressed compared to unsuppressed.

Want to see how much pressure is coming out of that gap? Wrap a piece of T-shirt or jeans material round the cylinder / flash gap area, secure it with duct tape, and fire the gun. The pressure wave will generally (on all except low pressure rounds) cut right on through the material. On high pressure stuff like .357 Mag, .41 or .44 Mag, .454 Casull, .460 or .500 S&W, the pressure is much higher and the material gets shredded.

Which is a good reason why you should keep you support hand and thumb AWAY from that area when firing a revolver in a two handed grip.

Lastly, I'm curious, why a 1/2-36 thread?

Most cans take either a 1/2-28 or a 5/8-24 thread, a 1/2-36 is not standard, and would require you to make an adapter for the can as well.

And if you don't have a 1/2-36 adjustable die to clean up the threads with after single pointing them on the lathe, you will have to be very careful and precise in cutting them, making sure to use lots of cutting oil and a freshly sharpened 60° tool bit.

I wouldn't try it with a carbide or carbide insert threading tool, you need to grind a slight nose radius, equal to 1/8th to 1/16th of the pitch onto the nose of the tool bit, and also grind in the helix angle in order to get a near perfect thread this way, and that's really tough to do with carbide inserts. HSS (High Speed Steel) would be the way to go there.
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Old 11-12-2017, 11:31 PM   #7
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Quote:
Originally Posted by NYECOGunsmith View Post
Trying to suppress a revolver is a waste of time, as stated, a large portion of the sound escapes from the cylinder gap, and if you put a suppressor on the barrel, the back pressure will increase, so that sound level will go up, I did it for a customer who wouldn't believe me, and then demonstrated it to him with a sound meter suppressed and unsuppressed.

The sound level the meter registered went up 1 dB suppressed compared to unsuppressed.

Want to see how much pressure is coming out of that gap? Wrap a piece of T-shirt or jeans material round the cylinder / flash gap area, secure it with duct tape, and fire the gun. The pressure wave will generally (on all except low pressure rounds) cut right on through the material. On high pressure stuff like .357 Mag, .41 or .44 Mag, .454 Casull, .460 or .500 S&W, the pressure is much higher and the material gets shredded.

Which is a good reason why you should keep you support hand and thumb AWAY from that area when firing a revolver in a two handed grip.

Lastly, I'm curious, why a 1/2-36 thread?

Most cans take either a 1/2-28 or a 5/8-24 thread, a 1/2-36 is not standard, and would require you to make an adapter for the can as well.

And if you don't have a 1/2-36 adjustable die to clean up the threads with after single pointing them on the lathe, you will have to be very careful and precise in cutting them, making sure to use lots of cutting oil and a freshly sharpened 60° tool bit.

I wouldn't try it with a carbide or carbide insert threading tool, you need to grind a slight nose radius, equal to 1/8th to 1/16th of the pitch onto the nose of the tool bit, and also grind in the helix angle in order to get a near perfect thread this way, and that's really tough to do with carbide inserts. HSS (High Speed Steel) would be the way to go there.
I would use 1/2x36, due to most 9mm products using that pitch so people can’t interchange a .223/5.56 can on a 9mm and have a blow up.

In theory couldn’t I turn extra threads on the barrel to close the gap on the forcing cone? I think having a .38 suppressed revolver would just be kind of a neat thing to have.
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Old 11-13-2017, 02:06 AM   #8
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Yes you could turn more threads on the barrel to reduced the flash gap, but if you get it down to the minimum .002" it will bind up pretty fast due to unburned carbon build up.

And it won't be all that quiet even with a .002 gap.

The only guns I have ever found threaded 1/2-36 in 9mm are the Colt 9mm AR and clones of it. HK uses a 1/2-32 thread, but everyone else (and I have threaded a huge number of 9mm barrels over the years, particularly for Browning High Powers) ) uses 1/2-28, same as for a .223/5.56.

Advanced Armament Corp specifies 1/2-28 for most of their 9mm suppressors, but for the Evolution 9 and Ti Rant 9 models they specify either 1/2-32 OR 1/2-36 in SAE threads, or a M13.5x1mm LEFT hand thread
Gem Tech lists three thread sizes for their 9mm suppressors, 1/2-28, 32, or M13.5x1 LH.

I guess someone could thread on a .223/5.56 suppressor by accident to a 9mm barrel, and have a bad day, but it would have to be in the dark, or they would have to have two suppressors and get them confused and not look at the muzzle end when threading it on, etc.

As long as you have enough meat still on the barrel at the muzzle when you thread it to contain the pressure, it doesn't matter what thread you use, as long as it is perfectly concentric with the axis of the bore, and matches the threads on the suppressor of course!

Good luck with your build, post a video with the results so we can "not hear it"!

PS, a potato reamed through with a 3/8" drill bit and stuck firmly on the barrel of a revolver suppresses a .38 Special pretty well in a pinch..........just ask the IRA.
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Old 11-13-2017, 07:17 AM   #9
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I seem to recall some body selling a barrel for Dan Wesson revolvers that had a changeable barrels that had a extension on it to attach a suppressor, you would set the barrel gap to .002" and lock it down and it would help quiet it up some. Only problem with that tight of a barrel gap is you have to keep it clean or it would jam up after a few cylinders of ammo fired, You could test the suppressed revolver thing pretty easy with a 2 liter bottle and some tape but you did not hear it [get it] from me.

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Old 11-13-2017, 09:12 PM   #10
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Quote:
Originally Posted by linny View Post
I would use 1/2x36, due to most 9mm products using that pitch so people can’t interchange a .223/5.56 can on a 9mm and have a blow up.

In theory couldn’t I turn extra threads on the barrel to close the gap on the forcing cone? I think having a .38 suppressed revolver would just be kind of a neat thing to have.
as mentioned , 1/2 x 28 is standard , nothing I have is threaded for 1/2 x 36.
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