ar 15 barrel dimensions

[redneckdan]

does anyone have a blue print for the standard contour ar-15 barrel? I have a possible project involving the turning and threading of a blank to fit it to an AR reciever.

[danski26]

Thats a pretty big "complicated" project. You do know that the barrel is not threaded like a bolt gun would be but indexed for the barrel nut that is threaded into the reciever right?

Or is this something i haven't seen "wich is very possible as i have only been working on AR's for 4 years full time more or less". Are you going to thread the barrel directly into the reciever without a barrel nut?

PS...the Shilen barrel website gives blueprints for some of the contours.

[Whaump 'em]

The barrel is threaded over the the chamber like many rifles, but a barrel extension is threaded onto it that has the locking lugs for the bolt. The headspace is set by how far it's threadded on, and then it's locked with an indexing pin that mates to the reciever.
The lathe work on an AR-15 barrel is the easy part, making the tooling to drill the indexing pin hole, and pinning the front sight or gas block inline with the indexing pin will take some time.
And if it's not a 223 Rem. you'll need to decide on where and what size to make the gas port.

[danski26]

I'm sorry i was not clear. That is what i meant when i mentioned that it was "indexed" for the barrel nut. The comment redneckdan made about "threading a blank to fit an AR reciever" is what threw me for a loop. If he would have said thread a barrel to fit a barrel extention all would have been right in the world. ;-)

[redneckdan]

see...I don't know enough to knw what I don't know. I do think this project is definitely in the realm of reality for me. I just finished helping with a garand rebarrel project and once we got down to the nitty girtty of doing it, it wasn't really that hard.

The barrel would be installed the standard way, threaded for the barrel extension thinga ma bober. I would go with a gas port full size of the tube ID, .110 inches if I remeber correctly, and use an adjustable gas tube. The caliber I'm chasing is .30 HRT, kinda like a .300 whisper with more bawls. The .30 HRt is a 6.8 SPC ramed into a .30 herret die.


Danski, if'n yer willing, I'd definitely like yer help as a source of information to consult with every now and again.

[danski26]

I'll give any help i can. I have never turned a barrel though. I am not a gunsmith/machinest, only a factory trained colt armorer.

Whaump'em is right though. The real trick is lining up the index pin with the front sight assembly. I suppose if you just went with a gas block in the front "adjustable" then the line-up would not be super critical and you might be able to make do with just eyeballing it. but that limits you to a scope or front sight on a barrel band or a lot of possible monkeying around to get the front and rear regulated.

If your just looking for that caliber i'm sure there are several barrel makers who can put one together for you so you can install on your upper.

[redneckdan]

i'm kinda lookin at it more for the fun of the project then just geting the caliber. I do have access to CNC mill and lathe capabilities. Can you recommend any manuals for building AR-15s, specifically installing barrels. thanks.

[danski26]

Colt Manual No. CM101 2nd Edition-Rev A.95

This is THE book for repairing colts AR's. I'm not sure if civilians can get it. Look around for it and i will do the same for you. If worse comes to worse i can run copies of pages from my manual for you.

[danski26]

www.specializedarmament.com

Ok found it quicker than i thought. This is a link to the factory colt parts dealer. You may have to call or e-mail with the manual numbers to make sure you get the correct one. Ken can answer any question for you.

[No_1]

Take a look at this: http://www.ar15.com/content/manuals/TM9-1005-319-23.pdf

it is : UNIT AND DIRECT SUPPORT MAINTENANCE MANUAL
(INCLUDING REPAIR PARTS AND SPECIAL TOOLS LIST)
RIFLE, 5.56MM, M16A2 W/E
(1005-01-128-9936) (EIC:4GM)

[Redleg99]

Maybe this will help: http://www.ar15barrels.com/profiles.shtml

Randall Rausch, the owner of AR15 Barrels.com, is pretty knowledgeable on this stuff.