old rifle chamber on new barrel

[joker1969]

Hi folks. I have a unique situation, I think. I have a Knights Armament SR-15 and what to change the barrel from 16" to a 20". For those who may not know, Knights uses a proprietary chamber to mate with their proprietary bolt. I was wondering if it were possible to buy a new barrel sans the chamber and then have a smith screw my old chamber onto it. Someone recommended that I "JUST BUY A NEW KNIGHT'S UPPER" with the 20" barrel and be done with it however I am not able to spend $1,000.000 on that set up at this point in my life LOL. I realize that I could just change out the "special" bolt for a standard one but that would defeat the purpose of me buying This rifle in the first place. So what say Y'all????

 

[243winxb]

buy a new barrel sans the chamber and then have a smith screw my old chamber onto it.

Chambers get cut, not screwed on. "joker"

 

[DocRock]

As per above, there is no "screwing on " chambers. They are integral to the barrel.

 

[BBBBill]

I have a Knights Armament SR-15 and what to change the barrel from 16" to a 20". For those who may not know, Knights uses a proprietary chamber to mate with their proprietary bolt. I was wondering if it were possible to buy a new barrel sans the chamber and then have a smith screw my old chamber onto it.

Barrel extension, not chamber. The chamber is cut into the barrel. The extension containing the locking recesses that match the bolt is threaded onto the end of the barrel. It might be possible to remove that without damaging it. The 16" barrel might have to be sacrificed to get it done.

 

[joker1969]

Thanks 4 the replies. I confused barrel extension with barrel chamber obviously. EXCUSE MEEE, LOL. Thanks to BBBBill. That makes sense. The thought did cross my mind that I would end up ruining my 16" barrel like you said if I had a Smith monkey around with removing the extension. Lots to think about.

 

[MrCleanOK]

AR-15 barrel extensions are torqued to the barrel at 150 ft-lbs. Once assembled, the chamber is finish reamed to establish headspace. Then the bore and chamber are chrome-lined if called for. Then proof load is fired. Then the gas port is drilled, indexed to the barrel extension.

Is it possible to reuse a barrel extension? Yes. Is it practical in most circumstances? No. And if you do try, your gunsmith better be very proficient with AR-15s.

It is not as simple as ordering a finished 20" barrel of your choosing and swapping the barrel extensions.

You'll come out money and time ahead to just sell the 16" upper and buy the 20" upper.

 

[Varminterror]

You'll come out money and time ahead to just sell the 16" upper and buy the 20" upper.

This.

Removing and reusing an extension is a hell of a lot of work just to keep a barrel. It may be possible to buy an extension from KAC and have a smith finish chamber a blank to the extension and bolt. Far more practical - but still a pretty considerable cost.

 

[Blue68f100]

I've removed the barrel extension on 1 AR barrel to see if I could improve the shot out cheap ($100) barrel. Just playing around to see what's involved. Besides the torque being off the chart, the index pin (hardened tool steel) in the barrel extension is actually into the barrel threads. So if you do not drill it out you mess the threads up in the process. Std M4 Barrel extension nuts are fairly cheap ~$30 from Brownell's. Not worth the effort as said.