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Posted: 1/16/2006 11:39:49 PM EDT
Anyone use one of these wrenches to correct a misaligned barrel/fsb? How would a misaligned barrel be corrected using this tool?
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A barrel extension wrench is for removing and installing barrel extensions. Tweaking front sights into alignment is usually going to require very little movement. Sometimes, simply loosening the barrel nut and holding the sight the direction you need to move it while re-torqueing the barrel nut will fix it. Make sure to grease the front of the barrel extension flange so the barrel nut torques against the grease and it will not force the barrel to move as you torque the nut. Very few people putting together AR-15's have a legitimate need for a barrel extension wrench. As I specialize in BUILDING AR barrels, I obviously use one every week, but there is no need to remove extensions otherwise. During the process of building a barrel, the extension gets torqued into place and then the pin is installed. The gas port is drilled at TDC as determined by the indexing pin. Moving/swapping the extension is almost always going to change the reference and the gas port/FSB is not going to be TDC anymore. For you non-mechanic types, TDC=Top Dead Center, a term used when working arond engines, usually the crankshaft position where cylinder #1 is at the exact top if it's travel in the compression stroke. In the case of barrels, you can think if it as 12:00. |
And it will almost always change your headspace too. Rainbow, Were you talking about removing the barrel extension, or using the barrel extension wrench as a means to rotate the barrel within the upper (to correct a canted FSB) after it is already installed? |
First, thanks for the responses.  Very informative. Second , no i didn't want to rotate the barrel with it in the upper receiver using a barrel extension wrench. I wanted to know if a mis-aligned index pin/barrel extension to FSB relation could be corrected by removing the barrel and adjusting the barrel extension in one direction or another. The aim is to correct excessive windage adjustment. I have a second bench vice coming in today and will try a re-install using the two vice method that someone described in another post. It may also just be a matter of using more lube on the barrel nut/barrel extension area of contact to prevent wind up of the barrel. |
| A heavy mallet will correct a slightly canted FSB... Ive even used a block of wood (small piece of 2x4 to protect the metal) and a heavy brass hammer to 'tweak' the FSB... Just don't hit it on the 'ears' of the FSB or you'll bend or break it... You want to support the upper then using either the mallet or wood/hammer to whack the open 'A' area (the whole 'A' frame) below the sights ears... |
Yes, someone else had posted suggesting this method in another thread ,but did not describe the finer points of going about it, like not hitting the "ears" of the FSB. This maybe my alternative fix if the two vice re-install does not work. One question would be after this type of fix does the FSB , or perhaps the whole barrel, eventually work its way back into a canted position? 
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FWIW, I have never seen a barrel extension "wrench", although like the sockets designed and used primarily by Armalite; I have seen barrel extension sockets (which fit into the chamber end of the barrel extension locking into the actual lugs, like the bolt and are used in conjunction with a barrel wrench to tighten the barrel nut when installing a new barrel) for both the AR15/M16s and the AR10s. Mike ps - sorry cannot say when or where as these items are rarely seen outside of the company listed above, which if my info was correct, were the first to machine and use such a device for mounting and un-mounting barrels........, I can tell ya they are slick little devices and make assembly and dis-assembly much easier. |
It is a permanent fix... |
Potatoe Potato... Brownells Link also lists them as a "wrench", even if they are more like a socket. 
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WOW, was not aware you could actually buy one of those Randall, as at the time I saw the ones I have seen and used they were "handmade" by a machinist friend, who told me that Armalite held the patent on them...... Learn something new everday around here, and I'm gonna have to add one of those little devices to my AR toolkit, (as the friend wanted way too much at the time to make me one). Thanks for the info. Mike |
I hand made my first ones too. Now they are easily available and the ones from Brownells are very well made. I have both of them now. |
True, it seems to be like a socket. I guess i went by a description of the tool i saw on a gunsmithing tool web site when i originally posted. Hope i did not cause any confusion. |
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