[regency]

So after lots of practice i may have finally figured it out, Maybe. First 2 pics below are the first attempt, and i somehow got in my head that .002 was .020 so these were undersized a bit. Next 2 pics i think i went too deep on the threads and made them very sharp. And the last pic i think is just right. Ive got to figure out which brake i want so i can order it and test these plugs. Who knows, i may be back to the drawing board!!! I am no machinist, im trying to do my very best with what little i know. Any help will be greatly appreciated.

 

[hottarod]

So I'm assuming you have a lathe with the abiltiy to cut threads?

I don't know the tech. I assume you have some sort of charts or info that tells you what diameter pipe you start with to cut a thread and how deep it should be cut.

 

[regency]

Yes i have a lathe and there are charts and tools available for the tech info. Also thread pitch gauges which you set on the threads and see if they match. All of this stuff i dont have right now unfortunatly. But i did lots of research on the web, weeding good from bad info. I am by far no where near ready to do my own barrel yet as i need more tools for other parts of this job.
I have the lathe of course, micrometers, dial calipers, dial indicator with mag base, and a few other precision tools.
Ive learned that on barrels, cuts to the muzzle must be made from the bore out. Threading must be done concentric to the bore not the outside of the barrel. The one thing that im missing is the actual spec sheet for the threads of an AR-15 barrel, that would help tremendously.

 

[Marlin 45 carbine]

machinists handbook has all you'll need to refer to.
just find the thread size/pitch you need.
sorry, I don't know the thread of an ar.

 

[hottarod]

Found this diagram from some discussion about barrel threading.

 

[tri70]

I believe the common AR pitch is 1/2-28.

Brownell's has a good selection http://www.brownells.com/search/index.htm?k=Muzzle+brake&ksubmit=y

 

[hottarod]

I have been reading that a lot of people cut the threads to about 80 percent on the lathe then finish them with a mandrel type thread cutting die.

 

[regency]

Yea the pics above are 1/2-28. I just needed to know length of thread and how wide the shoulder behind them needed to be. The pic you put up hottarod is just what i needed, thanks for that. Marlin 45, i think i have that handbook somewhere ill have to look for it.