BCL 102 Barrel Extension

[Horse96]

Hello,

So the guy in the video makes a good point. Barrel receiver extension wobble, when eliminated, can reduce groups by 1/3. Thought I'd put it out there. My ballistic advantage arms barrel's extension fit into the BCL 102 receiver not snug at all. Given that in my review I was able to get some decent groups, I was thinking that if I got the BAT extension, and maybe filed it in, that I would see an increase in my accuracy? Thought I'd put it out there and see where others were on the idea. It makes sense, eliminate all wobble, especially on the barrel, and you get a good shooter.

https://www.youtube.com/watch?v=pJL-IscH_jo

 

[b_w.]

Interesting. Have read a lot about using locktite to reduce the play. Getting a a new extension fit is going to take a lot of time.

 

[beltfed]

If you watch this guy’s other videos he drones on about bolt carrier tilt. That’s enough for me to discredit everything he says about wrenching on ARs right there.
A lot of this sh!t was hashed over decades ago.
If the play is not removed when your barrel nut is threaded and tightened down, take it off and coat your extension with either blue or red lock tight before putting it back into the receiver. Most times I find anti-sieze works just as well, and use blue over the red. If this doesn’t work and there is still play after torquing the receiver is suspect, and should probably go back to BCL. Edit: I see you are using an aftermarket barrel. How is the fit with the original barrel? I’d recommend trying anti-seize first see what that looks like torqued down.
Hand tighten the barrel nut to snug and then torque to the next gas tube port. Your gas tube should be perfectly centered and not bind on either the nut or the gas key.

If you want to go shimming and fitting a custom extension into your receiver go nuts.

 

[trigger'06]

I have been researching this for a while.
Both Rocksett and blue Locktite have their pro's and con's. Both need "help" to separate bbl/reciever.

Some companies go as far as a themal fit(reciever in the oven, bbl in the freezer) on their rifles.

On my 102 I found approx .030 play at the reciever/bbl interface with stock bbl, some noticble play with the bbl nut loosened.

On my previous range session I was getting 5-6 moa with Hertenberg, 1 1/2-2 moa with 168 and 175 GMM.
I also thought scope mount might be a little loose, detachable qd type.

Blue loctite type locker, tighten scope and off to the range.

After zeroing, first five shot group with 168 GMM was .72. Second was .86. The last three shots on the next group opened up to 2moa, but the barrel was getting warm.
Hertenberg was shooting 2-3moa.

I haven't been able to get back to the range for a longer session to cofirm or deny the initial findings.

My AR15 was to get the same treatment but when I removed the bbl nut i couldn't pull the bbl out easily, so I guess it's tight enough.


Remember if you do this it will take extra measures to separate bb and upper.

A precisely machined bbl extension does have merit. It would be nice to have a lathe.

 

[Horse96]

My barrel and extension fit is sloppy. I am going to try the indian head gasket shellac compound. Loctite is not heat tolerant, the gasket compound is. The compound was $35. The BAT machine barrel extension is $50 USD. I guess fitting time would get expensive as the steel is hardened. I might order the extension anyway as it should be good for the life of the gun. I've never changed an extension before. It looks pretty straight forward with the right tools though.

 

[beltfed]

My barrel and extension fit is sloppy....I might order the extension anyway as it should be good for the life of the gun. I've never changed an extension before. It looks pretty straight forward with the right tools though.

Are you a machinist?
If not you might want to do a little more research.
With the new extension, you are most likely looking at a new barrel and possibly a new bolt with that barrel.

Edit to add some links:

https_://308ar.com/ar-10-barrel-extension-ar308-barrel-extension/

Here’s a decent write up of doing your own barrel and extension - although I believe his numbers are off on the torque of the extension. I believe 175 ft/lbs is the correct number.

https_://rifleshooter.com/2014/05/building-machining-an-ar-15m16-m4-barrel-from-a-blank/

And one more from Lightfighter discussing the ‘bedding’ of the extension in the receiver:
http_://www.lightfighter.net/topic/bedding-the-ar-barrel-extension

 

[CODFan]

Yup. Going to potentially create head space issues.

On another note, I found the fitting of the Gen1 BCL barrel to be very tight. Could just be my rifle.

Even needed a soft mallet to seat the barrel.

 

[Horse96]

Hmm, shellac for now. If that works, all is good. With factory ammo, I did notice a tendency for it to throw a round on 5 shot groups. So, maybe the shellac will fix this? Fingers crossed.

On a side note, the bcl barrel and extension seemed to fit a little tighter than the ballistic advantage, there was still some play, but it was a little tighter.

 

[b_w.]

My barrel and extension fit is sloppy. I am going to try the indian head gasket shellac compound. Loctite is not heat tolerant, the gasket compound is. The compound was $35. The BAT machine barrel extension is $50 USD. I guess fitting time would get expensive as the steel is hardened. I might order the extension anyway as it should be good for the life of the gun. I've never changed an extension before. It looks pretty straight forward with the right tools though.

I twisted a barrel out of the extension once accidentally removing a rocksetted muzzle device and it resulted in a new barrel. No armorer would touch it and the wait time to have a qualified person look at it was months. At that there was no guarantee it could be fixed. Most guys viewed resetting it as a huge liability.

 

[Robmcleod82]

I twisted a barrel out of the extension once accidentally removing a rocksetted muzzle device and it resulted in a new barrel. No armorer would touch it and the wait time to have a qualified person look at it was months. At that there was no guarantee it could be fixed. Most guys viewed resetting it as a huge liability.

Seriously? Why spin it back on check headspace and rock on. Not sure where the paranoia comes from?

 

[Uisge]

I’d probably use locktite bearing mount compound (as mentioned in the write up) before I used threadlocker for the receiver extension, however in a pinch it could work, the gel or glue stick version would probably be better or leave a bottle of locktite open for a few days and it will thicken up a bit. You could gently peen the receiver I guess as well if you know what your doing?