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DIY SKS Barrel Threading
tr fox
Member Posts: 13,856
Here is an update of my question about threading my SKS Chinese Paratrooper barrel for a flash hider. My original post was:
http://forums.GunBroker.com/topic.asp?TOPIC_ID=612843
Most of my adult life as a gun owner, I always thought that threading barrels and cutting and crowning barrels could only be done by a highly skilled machinist/gunsmith with a shop full of complex tools. I wanted to thread the barrel of my SKS, after I removed the front sight, but hated to pay $65-75 dollars for it. So, after watching a YouTube video by a guy that used to feel the same way I did about not DIY, but he went ahead and gathered the info, bought all the hand tools for about $65.00 (as I did) and he threaded the barrel on his Sagia. So I copied him and did the same for my SKS.
The project was totally successful and with what I know now, I could do the job in about 1/2 hour. The threads are perfect and the American made (paragraph 922r you know) flash suppressor looks great. I only had the hand tools I purchased for the job, a common vice bolted to a 2'X 5' 1/2 inch piece of lumber using the tailgate of my pickup for a work bench. I did it outside at night without a whole lot of light and after about 6 beers. Job still went perfect.
Next I think I will cut one of my old milsurp rifles down to 16.5 inches, crown the barrel and thread the barrel for a compensator. It's kinda fun really.
http://forums.GunBroker.com/topic.asp?TOPIC_ID=612843
Most of my adult life as a gun owner, I always thought that threading barrels and cutting and crowning barrels could only be done by a highly skilled machinist/gunsmith with a shop full of complex tools. I wanted to thread the barrel of my SKS, after I removed the front sight, but hated to pay $65-75 dollars for it. So, after watching a YouTube video by a guy that used to feel the same way I did about not DIY, but he went ahead and gathered the info, bought all the hand tools for about $65.00 (as I did) and he threaded the barrel on his Sagia. So I copied him and did the same for my SKS.
The project was totally successful and with what I know now, I could do the job in about 1/2 hour. The threads are perfect and the American made (paragraph 922r you know) flash suppressor looks great. I only had the hand tools I purchased for the job, a common vice bolted to a 2'X 5' 1/2 inch piece of lumber using the tailgate of my pickup for a work bench. I did it outside at night without a whole lot of light and after about 6 beers. Job still went perfect.
Next I think I will cut one of my old milsurp rifles down to 16.5 inches, crown the barrel and thread the barrel for a compensator. It's kinda fun really.
Comments
As long as the hole in the end of the flash hider is large enough though. So that any misallighment won't cause the bullet to hit the end of the flash hider on exit. You will come out smelling like a rose.
Mounting a device like a suppressor, that has a requirement for a much smaller exit hole. Would be a entirely different story.
No way your going to get the flash hider mounted concentriclly with the bore diameter, by using hand tools. Specially if you have to remove some metal from the OD of the barrel.
As long as the hole in the end of the flash hider is large enough though. So that any misallighment won't cause the bullet to hit the end of the flash hider on exit. You will come out smelling like a rose.
Mounting a device like a suppressor, that has a requirement for a much smaller exit hole. Would be a entirely different story.
How do you figure that? The thread starting guide on most of the hand threading tools I've seen have a barrel insert portion. It would be virtually impossible to not get the threads aligned with the bore, unless one was using a starting guide for the wrong caliber, or if one's barrel was worn excessively so the bore-guide "wobbled" in the bore.
For example, this threading kit from CNC Warrior: http://www.cncwarrior.com/ProductDetails.asp?ProductCode=25145
quote:Originally posted by rufe-snow
No way your going to get the flash hider mounted concentriclly with the bore diameter, by using hand tools. Specially if you have to remove some metal from the OD of the barrel.
As long as the hole in the end of the flash hider is large enough though. So that any misallighment won't cause the bullet to hit the end of the flash hider on exit. You will come out smelling like a rose.
Mounting a device like a suppressor, that has a requirement for a much smaller exit hole. Would be a entirely different story.
How do you figure that? The thread starting guide on most of the hand threading tools I've seen have a barrel insert portion. It would be virtually impossible to not get the threads aligned with the bore, unless one was using a starting guide for the wrong caliber, or if one's barrel was worn excessively so the bore-guide "wobbled" in the bore.
For example, this threading kit from CNC Warrior: http://www.cncwarrior.com/ProductDetails.asp?ProductCode=25145
Don't let a old fart like me, pee in your Cheerios. You can mount a can or whatever on the end of your barrel, anyway you freeken please.
No way your going to get the flash hider mounted concentriclly with the bore diameter, by using hand tools. Specially if you have to remove some metal from the OD of the barrel.
As long as the hole in the end of the flash hider is large enough though. So that any misallighment won't cause the bullet to hit the end of the flash hider on exit. You will come out smelling like a rose.
Mounting a device like a suppressor, that has a requirement for a much smaller exit hole. Would be a entirely different story.
The above in red makes sense and I will remember that if I ever mount a suppressor. BTW, I did not have to remove metal from the OD of the barrel. Many people said I would have to but CNC Warrior said I did not have to. CNC Warrior was correct.
quote:Originally posted by competentone
quote:Originally posted by rufe-snow
No way your going to get the flash hider mounted concentriclly with the bore diameter, by using hand tools. Specially if you have to remove some metal from the OD of the barrel.
As long as the hole in the end of the flash hider is large enough though. So that any misallighment won't cause the bullet to hit the end of the flash hider on exit. You will come out smelling like a rose.
Mounting a device like a suppressor, that has a requirement for a much smaller exit hole. Would be a entirely different story.
How do you figure that? The thread starting guide on most of the hand threading tools I've seen have a barrel insert portion. It would be virtually impossible to not get the threads aligned with the bore, unless one was using a starting guide for the wrong caliber, or if one's barrel was worn excessively so the bore-guide "wobbled" in the bore.
For example, this threading kit from CNC Warrior: http://www.cncwarrior.com/ProductDetails.asp?ProductCode=25145
Don't let a old fart like me, pee in your Cheerios. You can mount a can or whatever on the end of your barrel, anyway you freeken please.
Is that your best physics/geometry/engineering/machining explanation? I'm not impressed by the "logic" of your argument.
How do you conclude that a thread-guide cannot give the tolerances needed to be within spec for a suppressor? Do you think that every guy who tries to cut threads on a lathe has some "automatic" alignment that assures the threads are cut concentric to the bore?
I'm not interested in getting in some p i s s i n g match; I'm interested in hearing logical argument about why one would conclude a thread-guide is supposedly inherently inaccurate. Have you used a properly made thread-guide to cut threads and measured how concentric the threads were -- and found problems that have brought you to the conclusion that guides are somehow inherently inaccurate?
To darn many variables in barrel diameters to use a one size fits all tool...
"One size fits all"?
Are you suggesting thread-starter guides are "one-size-fits-all"?
I'm beginning to think some of you are trying to be critical, suggesting certain tools are inherently inaccurate, when you don't even understand the tools being discussed.
quote:Originally posted by mrbruce
To darn many variables in barrel diameters to use a one size fits all tool...
"One size fits all"?
Are you suggesting thread-starter guides are "one-size-fits-all"?
I'm beginning to think some of you are trying to be critical, suggesting certain tools are inherently inaccurate, when you don't even understand the tools being discussed.
May I suggest you not be the pot calling the kettle color.
You can use any hand tool you please, to do anything you want to. The results will reflect your own understanding of the hand tool, the work piece, and the limits of which the operator can mesh the two.
From a prefessional, who has worked in the field of gunsmithing for 30+ years, yes, there is a much better way to assure success. A slightly off barrel device thread, that is only measured in thousandths of an inch, can have a very enlightening effect to the amatuer. But we all have to realize and learn from our mistakes along the way sometime. Just some learn harder than others.
Just from this statement
quote:How do you conclude that a thread-guide cannot give the tolerances needed to be within spec for a suppressor? Do you think that every guy who tries to cut threads on a lathe has some "automatic" alignment that assures the threads are cut concentric to the bore?
You can tell you have not a damn clue of what you are saying or suggesting. A slightly out of alignment in a can, can, and does act like a shrapnal grenade, in your face.
Best
EDIT 1
quote:Lathe-cut threading is measured within certain tolerances; do you have any objective evidence (numbers) on the tolerance differences between lathe-cut threading and guide-cut with "hand" tools.
(Extreme levels of precision are achievable with proper hand tools and precision guides. There is no "magic" that happens just because someone has a "big machine.")
Yes, there are some hand tools that can be extremely accurate. They must be used properly, to do so. As for the thread guides. They usually are close enough, and if one wanted to get one closer, they could modify it, for a 3 point attachment, that is adjustable, if it does not already have one.
As for the threading die itself, there are some that are made to lay down the major, and minor thread pich diameters, of the thread you need. Like anything in the firearms industry, they are usually, not of the standard, easy to find, in the general machine shop industry.
However, I do know some local machine shops that do stock a variety of firearm related tooling, for just such occaisions.
Best
quote:Originally posted by competentone
quote:Originally posted by mrbruce
To darn many variables in barrel diameters to use a one size fits all tool...
"One size fits all"?
Are you suggesting thread-starter guides are "one-size-fits-all"?
I'm beginning to think some of you are trying to be critical, suggesting certain tools are inherently inaccurate, when you don't even understand the tools being discussed.
May I suggest you not be the pot calling the kettle color.
You can use any hand tool you please, to do anything you want to. The results will reflect your own understanding of the hand tool, the work piece, and the limits of which the operator can mesh the two.
From a prefessional, who has worked in the field of gunsmithing for 30+ years, yes, there is a much better way to assure success. A slightly off barrel device thread, that is only measured in thousandths of an inch, can have a very enlightening effect to the amatuer. But we all have to realize and learn from our mistakes along the way sometime. Just some learn harder than others.
Just from this statement
quote:How do you conclude that a thread-guide cannot give the tolerances needed to be within spec for a suppressor? Do you think that every guy who tries to cut threads on a lathe has some "automatic" alignment that assures the threads are cut concentric to the bore?
You can tell you have not a damn clue of what you are saying or suggesting. A slightly out of alignment in a can, can, and does act like a shrapnal grenade, in your face.
Best
I'm not getting any explanation (I'm looking for numbers) on this alignment -- which I have NEVER suggested is unimportant.
Lathe-cut threading is measured within certain tolerances; do you have any objective evidence (numbers) on the tolerance differences between lathe-cut threading and guide-cut with "hand" tools.
(Extreme levels of precision are achievable with proper hand tools and precision guides. There is no "magic" that happens just because someone has a "big machine.")
"WARNING: Threading should be performed by professional gunsmith."
Interesting note from the CNC Warrior site:
"WARNING: Threading should be performed by professional gunsmith."
Statements like that are included for liability reasons. That does not mean "only gunsmiths" can thread a barrel to within certain tolerances.
There are many competent people who work with tools who do extremely precise work even though their work is just a hobby.
I know a few papered 'Engineers' that are real hacks when it comes to 'hands on'.
If the OP knows GD&T, ie: positional tol, total run out, cylindricity, etc, I'd have more faith in his claim of 'perfect' threads, etc.
quote:Originally posted by competentone
quote:Originally posted by iceracerx
Interesting note from the CNC Warrior site:
"WARNING: Threading should be performed by professional gunsmith."
Statements like that are included for liability reasons. That does not mean "only gunsmiths" can thread a barrel to within certain tolerances.
There are many competent people who work with tools who do extremely precise work even though their work is just a hobby.