ArmaLite Vs DPMS Barrel Extension

[Earl o Sammich]

I was always under the impression that the barrels were interchangeable.  I just ordered a barrel from Ballistic Advantage and didn't even pay any attention to the fact that it said "This .308 chambered (DPMS style) barrel...."  I have AR10Bs and this is what the upper will be that the barrel goes o.  I see out on the home page it says that the barrel extensions are not dimensionally the same.  WEll I was curious and took the barrel off one of my AR10Bs and measured it up against the barrel I jsut received from Ballistic advntage.  They look the same to me.

 

Here is the reciever side of the barrel extension flange to the edge of the extension for both barrels as well as from the barrel base inside the extension to the edge of the extension.

 

 

[Earl o Sammich]

...Here is the extension diameter measurements and the a measurement from the Barrel base inside the extension to the front of the extension bolt lugs.  If the measurements in the photographs don't look like they are exact it's because I am somewhat handicapped having only two hands.  It's hard for me to hold a ruler, flashlight, camera and barrel all at the same time.  I measured using a strong magnifying lupe and they are with in a couple of thousandths, if not exact, I would say.  I going to assemble in a few days and test fire.

 

Anyone know of a source for AR10B upper receivers by the way?

[Earl o Sammich]

26 inch Lilja three groove on top. 18 inch Ballistics Advantege bottom.

[98Z5V]

All you're doing with those measurements is checking the exterior dimensions, and the headspace, in a sense, for a .308 Winchester round.

Get into the teeth in inside that barrel extension and see what you find - where the lugs on the bolt lock in.  That's what you need to focus on.

What you've measure doesn't matter, in the grand scheme of things. 

We've already got a whole big thread on the differences between the bolts and bolt carriers - there's where your meat and potatoes are.

I've already successfully built and run a complete Armalite AR-10 "guts" system in a DPMS-based receiver set - it works flawlessly.  Armalite complete BCG and barrel - and the recoil system, which really doesn't matter, system to system.

Edited March 2, 2018 by 98Z5V

[Earl o Sammich]

Thanks 98.  Where is this thread you speak of.

[98Z5V]

Somewhere in the General Section - it's probably several pages back now... 

[98Z5V]

Dig in.

All we did was measure BCGs and bolts - you are in a situation to provide information on the barrel extension internal dynamics.

 

[Earl o Sammich]

I'll get the mic out and measure internals (to the extent I can) tomorrow.  Lug width, inside diameter between lugs, max internal diameter,  What else?

[98Z5V]

Lug width, lug length, amount of taper (would be tough to measure, but visible differences between the two could be seen). Distance from where the lug ends to the breech face. Can't think of much else.

[Robocop1051]

You can still use the DPMS BA barrel in an AR-10, you just need a DPMS bolt to mate to it.