Gunsmithing Setting up AR barrel in lathe......

[wareagle700]

Where do you clamp the jaws? On barrel extension or further forward on barrel shank?

 

[wtopace]

What are you trying to accomplish?

 

[wareagle700]

Taking a 20" Lilja .308 AR barrel down a few inches in length, crown, and re-threading for muzzle brake.

 

[wtopace]

(Assuming your headstock is big enough) I would remove the extension, thread a long-enough custom female extension and run the entire barrel through the headstock with an outboard spider for alignment.

(If you have a receiver truing jig) You can dial it in like you would a receiver in a "dual cats-head" setup (like the receiver truing jigs, I have a few pics on my blog in my signature of mine that I use for smaller 20" barrels sometimes)

(I don't recommend this option) If you aren't really worried about axial alignment since it is just a brake, you could chuck it in a 3-jaw and indicate off the bore centerline the best you can at a single point near the muzzle. DO NOT use a silencer on this barrel or you risk damage.

(If you just can't make the above options work) You can also try setting it up in a 3-jaw on the extension and a steady rest on the muzzle end if your bed is large enough. Dial it in as you would with the outboard spider.

 

[wareagle700]

The brake will be a suppressor mount. I didn't know if turning between centers would be accurate enough or if I needed a jig to make sure it was turning 100% true.

I may just have someone do it for me who has the right tools and experience.

Thanks.

 

[RWSGunsmithing]

Make a extension to go around the barrel extension, I drilled and tapped a set screw in mine to hold it in place and chuck it up between your headstock, This is assuming you have a spider on the back side of your headstock though.

 

[wareagle700]

Thanks for the replies yall. To do this right may be asking a bit too much from our little lathe and limited equipment. I will look at it and see this weekend when I make it out to the shop. If I have any doubts, I am within driving distance of some well known custom rifle makers and will let them knock it out for me.

Thanks again.

 

[MarinePMI]

I'd think setting up between centers would work easily for this...

 

[NXS338]

I made a set of barrel extensions I put on short barrels to be able to always reach the back spider of the headstock. I do this for all short barrels and have these already made for rem and savage with female threads, ar10 and ar15 is a tight fit over barrel extension with 3 brass set screws to ensure it stays in place. Then you can put all barrels no matter the length through head stock. I don't like to do anything like that between centers as I don't feel i can keep it as accurate as through the headstock.

 

[ugsly]

I also made a barrell extension that the AR15 barrell extension slides in and a collar that screws down to lock/hold it in place. Works quite well

Casey

 

[Ledzep]

I chopped and threaded an AR barrel on a 12x7" mini lathe. You just have to make some sort of rig to allow you to indicate the sucker in. I used a 4-jaw chuck and made an outboard spider that screwed onto my spindle. It took me for-fucking-ever to get it dialed in, but it worked. I've shot it with 2 or 3 different suppressors with no issues at all.

My 4 jaw held the muzzle end with about 1" sticking out of the jaws, the spider held the back end on the other side of the spindle.

 

[deadmilkman]

Make a extension to go around the barrel extension, I drilled and tapped a set screw in mine to hold it in place and chuck it up between your headstock, This is assuming you have a spider on the back side of your headstock though.

This.

Wes

 

[msalm]

You ever measure the run-out on most OEM extensions? Not that it really matters too much in this operation. Average .005-.012". BAT manufactured ones have always been under .001". This is barrel blank through the headstock for threading and chambering.

 

[wareagle700]

I decided to wait. I could probably do it on our current equipment but it would not be the best way and I don't want to booger up my barrel. I might let someone else have at it.

Thanks for the replies though, I learned something.

 

[McLarenross]

You never learn if you do not fail. Granted, failure costs money. Lotta good suggestions above, and I too have made extensions to thread onto 700 barrels < 20" to fit through my headstock and a slip over the barrel extension piece for AR barrels. Works great and lets me do as short a barrel as wanted without having to fight with a steady rest or other crap.

 

[wareagle700]

I'll experiment on an old barrel, not messing up this Lilja.

 

[wareagle700]

Make a extension to go around the barrel extension, I drilled and tapped a set screw in mine to hold it in place and chuck it up between your headstock, This is assuming you have a spider on the back side of your headstock though.

This is what he ended up doing.

I took the barrel to Joe Collier at Collier Rifles and he was nice enough to let me watch while he made the extension and threaded the barrel. Nice guy and very nice work.

Thanks.