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11/16/2007 7:24:19 AM EDT
I've noticed that I have a small (hair line) crack in the left side of my barrel extension. I don't know how long its been there, and I only noticed it beause I was had taken some time to remove the barrel from my upper because I am looking at switching uppers and making this barrel a dedicated .22lr barreled upper for my Ceiner kit.

Anyways, is there a way for me to swap out my barrel extension and still use the barrel with a new extension while just utilizing it for my ceiner kit .22lr upper?

I looked around in the build it your self tutorial but I didn't find anything about the barrel extension. Any help or guidance would be greatly appreciated. Thanks!
11/16/2007 12:05:34 PM EDT
[#1]
There is no tutorial since this is not easily done.  The basic problem is that the theads under the barrel extension are not indexed to the barrel.

If you could remove the barrel extension, the next extension will not line up the front sight base and gas port.  The gas port will have to be redrilled and the front sight base realigned.  If the front sight base was drilled and pinned, it will be very difficult reuse for those pins.

Of course, changing barrel extensions will change headspace to some degree.  Maybe none, maybe a bit more.

This is a gunsmith procedure not many like to do due to the aggrevation.  It is less trouble to start with a fresh barrel blank than to deal with existing problems.
11/16/2007 12:32:30 PM EDT
[#2]

Quoted:
There is no tutorial since this is not easily done.  The basic problem is that the theads under the barrel extension are not indexed to the barrel.

If you could remove the barrel extension, the next extension will not line up the front sight base and gas port.  The gas port will have to be redrilled and the front sight base realigned.  If the front sight base was drilled and pinned, it will be very difficult reuse for those pins.

Of course, changing barrel extensions will change headspace to some degree.  Maybe none, maybe a bit more.

This is a gunsmith procedure not many like to do due to the aggrevation.  It is less trouble to start with a fresh barrel blank than to deal with existing problems.


Good info, thanks! I can handle the above, especially since this is going to be a dedicated .22lr upper running a Ceiner kit (the gas port is irrelevant with the ceiner kit, I'm probaby just gonna put some silver solder in it to keep it from geysering gas) and I'm going to run an unrailed full length free float tube and just use optics and use the original FSB as extra parts for a later build.
11/17/2007 5:57:47 AM EDT
[#3]
IMO it's easier & cheaper in the long run to just buy a new barrel. If you don't mind the hassel then do the work yourself. If you don't mind the cost to replace, then have a smith do it for you.
11/17/2007 7:49:21 AM EDT
[#4]
Could you show a picture of the crack ??
11/17/2007 8:28:50 AM EDT
[#5]
If you are turning it into a .22 dedicated upper with a Ceiner kit, why even bother with the barrel extension?

Off the subject, I have a beater Guatemalan M16 barrel with BAD rifling.  I intend to bore out the chamber (1/2" for 2"), and then bore out hte rifling and reline it with one of those cheap .22 liners you can find for 10 bucks.  Pull off the Ciener chamber insert, and chamber the liner for .22.

I will leave the barrel extension in place as it is probably rusted into place like everything else in that parts kit.
11/17/2007 8:33:55 AM EDT
[#6]
exactly if your going for a dedicated .22LR upper then the extension being cracked is meaningless.
11/17/2007 6:40:21 PM EDT
[#7]

Quoted:
exactly if your going for a dedicated .22LR upper then the extension being cracked is meaningless.


I thought this might be the case, but I figured it would be more prudent to try and replace the extension as I was unsure of how the lower psi pressures generated by the .22lr would affect a small crack in an extension designed for 5.56 pressures. I guess I will take a crack at replacing the extension and see how it goes, I've got a replacement part on order from Del Ton. If it looks like I've bitten off than I can chew, I will just leave it as it and keep an eye on it while only running the ceiner kit (which was the plan all along).



Quoted:
Could you show a picture of the crack ??


I will try and dig up the digital camera from my wifes purse and tack a pic and post it...
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