thread and chamber ar15

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goettschmooney

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Anyone know where to find info on threading and chambering an ar15 as far as procedure. Got the dimensions off shilen website. Looking for more step by step procedure????????
 
Good luck. I built a Fulton Armory .308 last year and decided to use a Shilen barrel from another rifle. No one would tell me the dimensions for the bolt clearances, gas tube placement, anything. I assumed it would be easier for an AR 15, because of the standardization of dimensions, compared to the AR 10 series. Most of the interest in these rifles is from shooters, not builders. You'll need the barrel extension, which may be hard to find in this climate. Hunt on the net, some suppliers list dimensions, good luck.
 
jlmurphy said:
Good luck. I built a Fulton Armory .308 last year and decided to use a Shilen barrel from another rifle. No one would tell me the dimensions for the bolt clearances, gas tube placement, anything. I assumed it would be easier for an AR 15, because of the standardization of dimensions, compared to the AR 10 series. Most of the interest in these rifles is from shooters, not builders. You'll need the barrel extension, which may be hard to find in this climate. Hunt on the net, some suppliers list dimensions, good luck.
Click to expand...

accuracy speaks...think that is it has a book...set up and numbers. use this site for chamber set up.

i'll see if i can find the name of book,,,its out in the shop...just finished 2 ar 15 bbls.

mike in co
 
It is all basic machine work.

Greetings,
Re-barreling an AR-15 upper with a barrel blank is no more difficult than re-barreling a bolt action with a barrel blank, there is no magic it is just all basic machine practices held to vary tight tolerances. If you have the skill and equipment (lathe and vertical mill) to do journey level machine work it should not be a problem providing you have the additional special AR-15 and gunsmithing tools that it takes to do the job. That being said there are a couple of additional steps to do if you want to do it correctly. The gas port hole should be in a groove and not in a land. The worst case is if you put the hole in the junction of a land and groove ahead of the direction of rotation, tends to provide for faster fouling. If you have the skill to do this job you will be able to see how to make the special tool and set up required to put the gas hole in a groove and how the gas hole is clocked effects where you put the shoulder for the barrel extension to index the feed ramps. You will need the gas block and tube that you intend to use so that you can nail the dimensions when you turn down the barrel for the gas block. The head space is controlled with the bolt head and barrel extension. You will need these parts to cut the chamber to the correct depth. Variations in head space can be corrected by changing either or both of these parts as they come in different values and because of manufacturing tolerances there is some range available. You might get quite of a collection if you miss the headspace when you machine the barrel and try to correct it by changing the barrel extension and bolt head.

I suggest that you pay someone to do it for you.
Nic.
 
I want to learn it myself and don't care to have someone else do it , I learn nothing in that way. You brought up a lot of interestesting questions,but did not include any solutions or answers.I was aware of the points your brought up and wanted some suggestions or answers. I have barrelled bolt action rifles and know how to measure and headspace ,just applying such to an ar. Trying to determine what the correct tolerances are for bolt face to barrel extension face should be.Will further investigate gas port placement. It would require the extension be clocked to the barrel threads. Threading and chambering and barrel contouring are pretty easy as you suggest.I would not be swapping out bolt carriers and extensions to try to adjust head space. I would just set it up to minimum dimensions then check and ream deeper if necessary..Have you had some success doing ar barrels. thanks
 
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Thread and chamber AR-15 Barrels

Greetings,
I happened to be directed to your thread on AR-15 barrel threading and chambering. I am trying to gather as much info as I can before I start this project. I believe I have all of the tools and equipment needed to complete this. I have had experience chambering bolt actions as well. I'm just trying to make sure I'm not missing something. Did you ever find good information on this subject, and if so, would you share it?

Thanks,
Gary:)
 
I turn my AR15 tenons .810" diameter by .620 in length (allows .008-.010 gap between bolt and breech face). Thread 16TPI, if you use an extenstion from BAT Machine, you don't need a thread relief groove as the threads are relieved in the extension, and they're just the best extensions I've ever used. The chamfer at the edge of the chamber is needed for reliable chambering. I use somewhere around a 20 degree (from perpendicular) angle, and cut about 1/8" over chamber size. Use a good quality barrel and you'll have an AR that shoots better than any of the OEM AR's out there.
 
AR-15 barrel threading and chambering

Thanks for the information and dimensions on AR-15 barrel threading and chambering. By any chance would you have and dimensions for AR-10s ?:):):)
 
Actually I do, I just started building a few and will have to check at home tonight. Most of your dimensions can be derived just by measuring the bolt/barrel extension. The tenon is quite long on the AR10, but I don't remember the dimensions as I just did my first one last week:).
 
AR Service Rifle Dimensions

Goettschmooney - here are the dimensions for a Service Rifle barrel. From there you’re limited only by your imagination. Have fun.

HPC

ARdimensionsfinal.jpg
 
HPC, thanks for the info. Any Chance you could post it at higher res as some of it if is about unreadable when blown up?

Thanks!

Ian
 
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