Jump to content
308AR.com Community
  • Visit Aero Precision
  • Visit Brownells
  • Visit EuroOptic
  • Visit Site
  • Visit Beachin Tactical
  • Visit Rainier Arms
  • Visit Ballistic Advantage
  • Visit Palmetto State Armory
  • Visit Cabelas
  • Visit Sportsmans Guide

Installing a barrel extension


Recommended Posts

I used the search function but could not find it.

 

I am behind enemy lines in the People's Republic of New York so this may sound like a Why are you doing that?!?!? topic.

 

Anyway, I have a 24" Remington 700 Barrel (hunting profile) chambered in 30-06 which I am having replaced for a 30 inch bench rest profile and I got the bright idea to machine it to fit a DPMS 1st Gen LR-308 upper. The barrel will be rechambered to .308 Win and not have a gas hole inorder to make it a straight pull bolt rifle. The barrel will make it light enough to carry in the field and will be legal to have a pistol grip and colapsable stock if I desire to put one one. This configuration passes the NY SAFE act feature test because it is not a semi auto. As a bonus it can be used for hunting in PA which does not allow semi auto rifles for hunting.  

 

My questions are:

 

Is there someplace that I can look up the barrel extension installation specs?

Is there a specific torque to apply?

 

My gunsmith is going to be installing it, i am just trying to learn all I can about installing the barrel extension and headspacing.

 

Thank you

DSDMMAT

 

Link to comment
Share on other sites

That is an item I would request you let you gunsmith do !

He will be rechambering the barrel and can install the barrel extension at that time. It would be the smart solution, if you have a problem the gunsmith can fit it.

I did a barrel in 270wsm with a Win70 barrel like that and its a club now only shot once. It was not up to standard(Too Thin).)

Link to comment
Share on other sites

I fully intended on letting my gunsmith do it, I just wanted to read up on it so I understand what is being done. He is really good about explaining things to me, I just want to make the effort to understand it and be able to ask intelligent questions. I don't have access to the tools to do it myself ( not that I would try) in my previous career I was a helicopter mechanic for 20 years I understand tolerances, I am more interested in knowing the process and the terms before it is done. I hope that makes sense.

Link to comment
Share on other sites

The only barrel extension manufacturer I know of for large ARs is BAT Machine, you should be able to contact them and get a torque spec for their barrel extension.

SI-D does too... or at least they did when I bought mine from them.

I had them send a NiB barrel extension to PROOF Research to finish my carbon fiber wrapped barrel.

Link to comment
Share on other sites

175lb/ft.  I know you'll find different numbers across the web.  It's 175lb/ft.  Since it's going to be a single-shot, and you won't be drilling a gas port, it really doesn't matter what steps he takes in installing it.  He's going to have to trial-and-error the headspace, though.  Have fun taking that extension off and putting it back on a few times, while machining the extension for the proper headspace.  I don't know how many AR barrels he works on, but he's going to need a specific barrel extension installation tool to pull this off.

 

Chambering from the 7.62x63 down to 7.62x51 is going to be quite the chore - I'd like to hear how he's going to do this.

 

Good luck.  This neva been dun befo...

Link to comment
Share on other sites

Thank you for the responses. The rechambering is going to be done by cutting off the original remington 700 threads which will shorten the chamber before to smaller than the 308 and then rehambering it with the 308 reamer. I will lose about 1 inch off the barrel length but it doesn't really make that big of a difference. He does a lot of barrel work so the retreading and chmbering is going to be the easy part, he has never put a barrel extension on before and says he is looking forward to it. Something out of the ordinary for him.

Link to comment
Share on other sites

Im no gunsmith but I don't see the big deal. Chop off the ass end of the old barrel and sink a 7.62x51 reamer until it all cleans up. Re-thread and set extension to proper depth?  Should be pretty straight foward.

 

    All depends on the contour of the barrel , some don't have enough material to move the chamber forward & have enough material ( diameter ) to safely do this .Cutting off the org. threads & then rethreading for a Barrel Extension will take some thinking , but doable .

  Whats nice about it , as was mentioned , is not worrying about a gas port alignment to the indexing pin on the Extension .

 

  Tell him we need photo's  of the stages of the process . <thumbsup>

Edited by survivalshop
Link to comment
Share on other sites

He does a lot of barrel work so the retreading and chmbering is going to be the easy part, he has never put a barrel extension on before and says he is looking forward to it. Something out of the ordinary for him.

 

This fact will make this very interesting.  He needs to buy a few more tools, then.

 

    Cutting off the org. threads & then rethreading for a Barrel Extension will take some thinking , but doable .

 

 

First thing I thought about when I was reading the OPs latest post - Cut from x63 down to x51, and lose those threads that you need.  Recontour the barrel chamber area back down, so you can cut new threads, begin the headspace process after that, with the barrel extension at 175...

 

Gonna be a decent challenge, no matter what kind of machinist or gunsmith you may be.  In the long run, .308 AR barrels are pretty damn cheap, compared to the bill I'd hand forward for such a task.

Link to comment
Share on other sites

OP, you can buy a .308 AR barrel, spot weld the gas port shut - and you have a single-shot AR barrel that would be legal upon ANY inspection by ANY authorities.  I'm just sayin'...

 

  Or get an Adj. Gas Block that you can close the port up completely. <thumbsup>   I never though about the cost of the Gunsmith, An 308AR Barrel might be the way to go , the Gunsmith may just want to try the job out for his own experience . He might get more to do or make Barrels up to sell , just for this type of thing . <dontknow>

Link to comment
Share on other sites

Well I could probably get about 30- 50 bucks for my barrel then spend 250-300 for a barrel then deal with the gas port. Or I can take the barrel I got and put 250 into it and not have to worry about anything else. I get to learn the process and watch/ have explained the process which is worth the expense to me.

Link to comment
Share on other sites

^^^  That is based off the presumption that this works out.  You can nail a .308 AR barrel for cheaper than $250, from numerous places online. 

 

Not trying to be a downer to you, but there's going to be significant work involved in doing this.  It doesn't seem that you realize that, as wells as your gunsmith realizing that.  It won't be an easy affair, and you're the one paying for it. 

Link to comment
Share on other sites

Well I could probably get about 30- 50 bucks for my barrel then spend 250-300 for a barrel then deal with the gas port. Or I can take the barrel I got and put 250 into it and not have to worry about anything else. I get to learn the process and watch/ have explained the process which is worth the expense to me.

 

I say go for it. And if your gonna hang out and watch it being done take pics and post them up so everyone can see whats really involved.

Link to comment
Share on other sites

^^^  That is based off the presumption that this works out.  You can nail a .308 AR barrel for cheaper than $250, from numerous places online. 

 

Not trying to be a downer to you, but there's going to be significant work involved in doing this.  It doesn't seem that you realize that, as wells as your gunsmith realizing that.  It won't be an easy affair, and you're the one paying for it. 

 

I apreciate your thoughts however (please don't take this wrong); neither my gunsmith nor I am concerned with the ease of the task.  Nor am I concerned with how much it costs (that is one benifit of combat and combat pay). If I was concerned about ease of something I would buy something off the shelf. If I was concerned about the cost, I woud not be building a 3rd AR-308. The only concern right now is is there enough meat on the barrel to put the barrel extension on the barrel in the first place. Once I have the barrel extension in my hot little hand, we will be able to see if the project is actually feasible. If not i am only out the 60 dollars for the extension and pin. If it is then we are off on an adventure. The 24 inch remington barrel is a totally different profile than I can readily buy from a barrel maker and it will cost about the same when I special order it anyway.

 

My projects normally don't involve considereations more than quest for knowledge and experience when more I take them on. I have a bolt action 5.7x28 that was only built to be able to shoot the little cartridge from a boIt action rifle. It cost way more than twice the original rifle. It was built to satisfy curiosity and nothing else. The whole point of this exercise is to gain experience with what is possible and what is not. I figure the cost is much like taking a college class where I may or may not gain anything from it, other than experience and knowledge.

 

    

 

I say go for it. And if your gonna hang out and watch it being done take pics and post them up so everyone can see whats really involved.

I will try to get photos, hopefully he will not be so busy that he has to push the project off into my next deployment window. Some of my projects end up taking over a year to complete.

Link to comment
Share on other sites

I apreciate your thoughts however (please don't take this wrong); neither my gunsmith nor I am concerned with the ease of the task.  Nor am I concerned with how much it costs (that is one benifit of combat and combat pay).

 

Those projects make the BEST projects!  I see you're aware of it - which I didn't think you were.  Since you already are, and this is to "see if it can be done," then it'll be damn fun to find out!  I'm in!

 

I know of the benefits of combat and combat pay, too. Hostile Fire Pay, Hazardous Duty Pay, Combat Zone Tax Exclusion, etc.  All over it. Got all those, with TDY pay on top of it.  <thumbsup>

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...