Threading barrel for flash suppressor, need help!

Hello,
Sorry my ignorance, I'm just learning things between gunsmithing and metal lathe work.

I have a project right now, cut a HK SL8-1 rifle barrel, and install a 3" flash suppressor on it to give a total legal 16".
The suppressor will have the AR-15 thread.

My big problem is: What should I use to thread it? lathe or die?

Also, anyone know the spec for the AR-15 thread? My gauge shows 28tpi and 1/2"OD for the AR-15's barrels....can't find any die with this numbers.

Thanks in advance and Happy Holidays!
Ed

Ed,
Brownells should have the 1/2"-28 die.The lathe would normally cut a more accurate thread assuming the lathe is in good shape and the machinist knows what he is doing.You could set up the receiver in a 4 jaw chuck with a steady rest close to the end of the barrel.Use a cats head to protect the finish on the barrel and shims around the receiver.Thread at a slow rpm.Practice on some scrap before attempting to thread the barrel.The prudent thing to do would be to thread the end of the longer barrel before you cut it just in case you run into threading problems.You'll have to look up your min and max pitch diameter for a 1/2"-28 thread and buy a set of thread wire gages if you want to cut an accurate thread.

Be careful that you attach the flash suppressor with an ATF approved method ,I believe they list the approved temperature for high melting point silver solder at their site,and I believe using a blind pin or tack welding is alright.Check the FAQ section to be sure.

One problem that you might encounter is a hard outer skin on the barrel,I've heard that some of the pistol barrels are hard to cut a decent thread on.

Good Luck!

[This message has been edited by Barry Briscoe (edited 12-14-2002).]

Thanks Barry,

I did remove the barrel out of the receiver ( I made a toll for it...HK want $1k for this tool), so I can attach the barrel to the 3 jaw chuck.

I still have to find a good place to buy thread cutting bits, I did try cut a thread on a piece of the barrel that I cut (the end piece), I turned the barrel down to 1/2" but I don't have any thread cutting bit, so I made one....thread don't look bad, the problem is...LOL, ended up being a reversed thread. I guess the right bits for it must have a right angle. I guess I'm learning from my mistakes...I'll order the lathe course from AGI 12 hrs of lathe....

About the ATF rules, I'm aware of it, just got my C2 license and 3" of books to read.

Happy Holidays!
Ed

Don't mean to point out the obvious, but putting a flash hider onto a post ban rifle would make it an Assault weapon, a flash hider counts as an evil feature just like a threaded muzzle would. Make sure you're putting on a muzzle break. As barry says, it must be permanently attached. High temp silver solder, tack weld or TIG are all acceptable. Check with the maker of the break first to make sure it's not classed as a flash hider.
Threading in a lathe is the only way to do it. The cost a 1/2 x 28tpi UNEF die is goona cost you would be better off spent on tooling.

If you want info on legalities as at our site:
http://subguns.biggerhammer.net/boardadmin/semimsgadmin.cgi

Any questions, feel free to email me.

Mike

Also...
If you cut a thread and it came out a reveresed (Left hand) thread, then you need to change the decion your lathes threading in. There should be a change lever/gear to change from L/H thread to R/H.

If you chuck is turning anti clock wise (looking towards the jaws from tailstock) then when you engage your half nuts, saddle should move to the left. This will cut a right hand thread. Being that you've just gone C2 you might want to have a look at:
http://subguns.biggerhammer.net/boardadmin/mgmsgadmin.cgi

I take it you have a type 07 FFL with C2 SOT?

What state you in?

Mike

Thanks for the information Mike, about legality....don't worry folks I do have it covered well, it will blind pinned and soldered.(IT'S A FAKE FLASH SUPPRESSOR!!)
About the lathe, I did try both ways..clock wise and counter clockwise and got the same results...(sounds crazy)reversed thread... it must be the angle on my tip.

I'm doing my second HK G-36 clone, and this time instead pay $220 for cut, turning, thread the barrel and parkerize...I'll do it all myself. Fake flash suppressor will be a G-36K look a like, but groved only to give the impression of cuts and at end the opening will be closed as per ATF specs with only the big enough hole for the bullet go thru.

Yes, my License is 7- Firearms manufacturer and I'm in Florida.

You can go here to see my first clone G-36:

http://www.villagephotos.com/pubbrowse.asp?selected=115695

Thanks,
Ed

[This message has been edited by ARAKUZI (edited 12-15-2002).]

[This message has been edited by ARAKUZI (edited 01-18-2003).]

I guess that I'm confused. If the chuck is turning towards you and is feedin to the left it has to be a right hand thread or my mind has gone away this evening. Butch

I'm just guessing here, but doesn't a Flash supressor have a LH thread?

It would make sence to me that it would be threaded in the opposite direction of the twist of the bullet, so that it would tighten instead of try to unsrew.

It sure sounds like you turned a RH thread, and if its the right pitch and Dia, I dont see why the Flash supressor wouldnt screw onto it, unless the Flash supressor has a LH thread.

If what I just said makes no sence, just ignore it.

AR-15 is 1/2 x 20 RH thread. I agree. If the lathe is rotating counter clockwise looking from the tailstock at the head. And if the carrige is moving to the left it must be a RH thread.

Some of the flash hiders will have a thread that is slightly mis-sized so you might check the diamiter of the brake you are using.

Well, it's being a long time...I got all figure out....was a little lever to invert the carriage Lt to Rt or Rt to Lt in relation with the lathe rotation. I did 3 threads to learn and went to a barrel and it come out perfect!! I was very excited, I had to clean just a bit with a die. I also got a threading 60 degrees cutting carbide that worked great. This is a learning process that I wish I have had a chance to do on my younger age, I really enjoy it and thanks for all you folks that droped a word.

PIC of my third thread



Regards,
Ed

BTW Kent, is 1/2 X 28 tpi RH

Ooops, Yep. I intended to type 28. Brain fart I guess. Sorry.

is it a selective fire version or a post ban SBR?

Are you looking to do this?

I was fixing to add a note that my Ruger AC-556 was threaded to allow M-16 thread on parts to fit it. It has 28 tpi, but somebody already explained that information.
Arakuzi,
I would like to know where in Florida your at? Thanks,
David from Jax