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Posted: 4/10/2003 12:30:13 AM EDT
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Am replacing the regular handguards with free floats, front sight post and gas tube removal - no problem, but...even with a barrel nut wrench and aluminum barrel vice clamp shoes from Brownells, I can't get enough torque on the nut to loosen it. To avoid marring the barrel in the aluminum shoes in the vice I wrapped the barrel in tacky carpet backing, but the barrel and upper still turn when I crank the wrench. Should I abandon the carpet back wrap and just clamp down on the barrel for all its worth in the aluminum shoes? Or should I attempt the put the upper receiver in the vice and then turn the nut, I am concerned about damaging the upper with this option. This is much tougher than I thought it would be. Any tips? Thanks guys |
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Suggest ya get one of these "Armorer's Action Block", from Bushmaster or DPMS, which will hold and protect your upper in the vise, then give it another try. [img]http://www.bushmaster.com/shopping/gunsmith/Images/om-003-withupper.jpg[/img] Mike PS - here's some helpful hints posted a while back, check the freezer portion near the end: [red][b]Gunsmithing TIPS from Chris[/b]: Barreling Uppers... Installing a barrel is really pretty simple. Solving some of the problems you can run into isn't. Probably the most common problem is excessive windage present after the installation. The rear sight will be cranked all the way to one side. This is one time the manual doesn't help much, most military armorer learn this trick early. Here's how to fix it. Clamp the barrel in a vise, using barrel blocks. Line up the front sight carefully on a vertical line, just like the book says. First tighten up the barrel nut - hand tight, not torque to prevent damage to receiver. Now, look at your receiver. Chances are it's leaning off to one side -when compared to the front sight. Using a non-marring hammer, hit the side of the carrying handle, as near to the front as you can. This will rotate the receiver slightly to one side or the other. Here's the trick, hit on the side that the rear aperture is furthest away from. In other words, try to move the receiver towards the rear sight. Be careful, you don't have to kill it, just a firm tap will usually do the trick. If the barrel is straight, aligning the receiver forging with the front sight forging will usually put the windage adjustment right in the middle, and it takes about a minute to do it. Simple! One other trick we should mention is for when you are torquing on a barrel nut and everything locks up. A squeaking noise, then it's like it's welded right there. The surest way to break something is to keep trying to loosen it. [b]This trick is so simple, we couldn't believe it. Put the whole assembly in the freezer, and leave it overnight. This gets some differential expansion working for you. Pull it out the next day, and it will almost always come loose. We recommend using an action block,[/b] like the one we sell, and clamping on the receiver to prevent breaking the index pin when doing this. A really good wrench, like the heavy duty one we sell, will prevent ruining the barrel nut.[/red] |
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Thanks, everyone. Action block on the way from Bushmaster. How much of a problem is it to end up with the upper canted slightly vs the front sight? If the barrel nut is just finger tight on reassembly can't I just adjust/twist the barrel enough to get the alignment needed before torquing the nut down? Shouldn't have to tap on the handle like the gunsmith tip above suggests? I will find out tomorrow I guess when the block arrives on the brown truck. This is great fun and super support. |
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Thanks guys, I got the old one off and the new free float nut and sleeve in place. The Bushmaster action block is the way to go for sure. I got one and it did the trick. Torque for new nut about 60-70 lbs I think by the time I got the gas tube holes lined up. Have a JP free float tube and a Bushmaster 3 rail gas block. To get the tube to thread onto the barrel I had to mill down the last rail nubs, buttstock side. Otherwise it's stressing the tube and nut during tube screw on, with good chance of screwing up the threads. Without that mod its too tight. Got some shots off last weekend, almost done sighting in the scope. And discovered I had the JP kit hammer spring (yellow one) in backwards, with a couple of failures to fire after good chambering, just a little dimple in the XM193 primer. When flipped around the hammer delivers a lot more punch, at least to the touch on the bench. Off to the range tomorrow weather permitting to see what kind of groups I can get, and how that hammer spring works with XM193, otherwise its back to the mil spec spring and a little more trigger pull, but it sure is sweet with the yellow spring. This really is just great fun, and the support on this board is super. BTW how do you post pics? I will put up a photo once I figure it out. |
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