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Posted: 2/10/2004 4:22:21 PM EDT
| Looking at building upper from bare nuts barrel how hard is it ot intsall a barrel ext. and whats involved? any idea what it would cost to have it done for me? |
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Once the breech end of the barrel blank is properly machined to accept the new extension, installing it is easy. Just screw it on and torque it to 150 lb-ft. The hard part is then reaming the chamber to the correct headspace, drilling and installing the index pin, then locating and drilling the gas port out there for your desired sight base or gas block. Unless you are an experienced machinist / gunsmith I wouldn't bother. Just cough up the $ and go buy a complete, ready to install barrel of your choice. |
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If you're lucky, you can buy a new barrel extension, torque it on and it happens to line up with the old index pin/gas port. Check that headspace is good, and you're in business. If it doesn't happen to line up, the process will be longer, more expensive and more painful than it's probably worth. Torquing the barrel extension requires a barrel extension wrench (or an old bolt used in that capacity) and some barrel vise blocks. |
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If the barrel you are considering using is REALLY stripped with no extension or front sight base on it, the process can be a real pain and tooling intensive. Your odds of screwing on a new extension and getting the proper locking lugs-to-gas port alignment are about 1 in 1000. Even if you were so lucky with proper "clocking" of the extension, the headspace may end up being either too short or too long. If too short, you could ream the chamber as long as the chamber is not chrome plated. If it's chromed, your screwed. It can't be finish reamed. If the chamber is too long, then you would have to turn down the front of the extension or the back of the shoulder on the barrel to move the lugs closer to the chamber. Then you loose your lug-to-gas port alignment again. I am presuming that your stripped barrel was also stripped of it's front sight base. Now if you were successful in getting all the above correct, then you have the issue of getting the the front sight base taper pin holes in your new front sight properly drilled and taper reamed to match the previously drilled holes in your "stripped" barrel. This is not an easy thing to do if you want the FSB to not be canted to one side or another. A solution here would be to use either a setscrewed gas block (no sight) or a clamp-on conventional FSB such as the one Armalite sells. As you can see, the attractive economics of buying a previously installed, "stripped" barrel vanish quickly when you have to go through all the B.S. I have described above. If you buy a true barrel blank to start with, the process is alot easier because you don't have to contend with previous machine work. Again, my recommendation is to use your stripped barrel as a tent stake or prybar in your shop and go buy a ready-to-install barrel assembly. |
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