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Posted: 9/3/2009 11:40:11 AM EDT
| i'll be putting on my barrel tonight and was curious how tight to put the nut on. Do I just arm it or is there a torque rating? heading to lowes tonight to get a vise and some materials to build an action block set |
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there are only 2 chemicals I will let touch my ar. mil tw25b grease and slip2000 oil, not motor oil Good luck building an action block set. Long ago I thought I could make one from dremeled 1x6 pine. After much cussing and eventual action block build success, I discovered that it gave too much in the vise when torqing a barrel. I ended up buying an action block. Whatever grease you use, make sure it doesn't thin out under heat. You want the grease to stay put to prevent the steel and aluminum from seizing together. Secondly, as another poster mentioned, don't over torque the barrel nut. You will have accuracy issues. |
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I was planning on using a teflon board, drilling and building similar to the DPMS claw style, and I'm pretty sure MW25B is good for assembly Post a thread in your hometown forum and see if you can borrow a barrel block or DPMS Panther Claw for your build. Torquing the barrel without the proper barrel block may cause you problems with undue flexing/stress on the receiver. Do it right, don't be cheap. 
40 to 45 lbs of torque seems to line the barrel nut up perfectly for me about 90% of the time. |
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Quoted: Not trying to hijack cyberhedz's thread, but I cannot get the barrel nut to align without exceeding 80 ft-lb. I would find someone with a reciever lapping tool and try to lap the reciever until the barrel can be tightened properly without exceeding 80ft lb |
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Not trying to hijack cyberhedz's thread, but I cannot get the barrel nut to align without exceeding 80 ft-lb. Don't exceed 80ft/lbs. Did you tighten/loosen, tighten/loosen, tighten/loosen, tighten/loosen? I've found in the past that tightening to ~55ft-lbs or so, check to see if teeth clear the gas tube hole, if not loosen and tighten again until I have clearance. Repeat several times. If you've tried this and still can't get it to line up, it may be time to break out a small rattail file and take the tooth down (which I've had to do before). Sucks, but it won't hurt anything. |
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Quoted: Quoted: Not trying to hijack cyberhedz's thread, but I cannot get the barrel nut to align without exceeding 80 ft-lb. Don't exceed 80ft/lbs. Did you tighten/loosen, tighten/loosen, tighten/loosen, tighten/loosen? I've found in the past that tightening to ~55ft-lbs or so, check to see if teeth clear the gas tube hole, if not loosen and tighten again until I have clearance. Repeat several times. If you've tried this and still can't get it to line up, it may be time to break out a small rattail file and take the tooth down (which I've had to do before). Sucks, but it won't hurt anything. I like to lap all of my barrels with brownells lapping tool. http://www.brownells.com/.aspx/pid=20220/Product/AR_15_M16_UPPER_RECEIVER_LAPPING_TOOL Make sure you follow rob78's advice on tightening and loosening several times. |
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Not trying to hijack cyberhedz's thread, but I cannot get the barrel nut to align without exceeding 80 ft-lb. Don't exceed 80ft/lbs. Did you tighten/loosen, tighten/loosen, tighten/loosen, tighten/loosen? I've found in the past that tightening to ~55ft-lbs or so, check to see if teeth clear the gas tube hole, if not loosen and tighten again until I have clearance. Repeat several times. If you've tried this and still can't get it to line up, it may be time to break out a small rattail file and take the tooth down (which I've had to do before). Sucks, but it won't hurt anything. Sounds like a solution, thanks. |
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How far past 80lb? I've not tried to exceed 80. If I had to wag it, I would guess about 120. You're about 80lbs. past where you outta be then. Tear the thing apart and hope you didn't booger it. 120 is waayy to much torque to be putting on an aluminum receiver with a steel barrel nut. Seriously, I doubt you really have that much torque on it. I'd guess the barrel nut teeth would begin to give a little by the time you got the torque that high. Just a guess, as I've never gone that high. I use a torque wrench and tighten to spec, like the TM says to do it, with the moly grease, the tighten/loosen routine, etc., etc. 
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How far past 80lb? I've not tried to exceed 80. If I had to wag it, I would guess about 120. You're about 80lbs. past where you outta be then. Tear the thing apart and hope you didn't booger it. 120 is waayy to much torque to be putting on an aluminum receiver with a steel barrel nut. Seriously, I doubt you really have that much torque on it. I'd guess the barrel nut teeth would begin to give a little by the time you got the torque that high. Just a guess, as I've never gone that high. I use a torque wrench and tighten to spec, like the TM says to do it, with the moly grease, the tighten/loosen routine, etc., etc. Sorry for the confusion but I have been using a torque wrench and have not exceeded 80 ft-lb. |
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Did you start it off at 30? It seems strange that it didn't align with any of the holes anywhere between 30 and 80lb. The two i've done aligned at 45 and 55lb. As I torque it in the vise block I hold a gas tube alignment tool (shortened piece of gas tube) thru the barrel nut against the gas tube hole in the receiver. When it lines up the tool slides home. And you're done. I don't know what procedure you used.
The only thing I can think of is to start over. I know brownells sells a tap and die for the receiver and barrel nut. Maybe you can clean up those threads and start fresh. I'm no gunsmith but thats what i'd probably be looking at. |
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OP, it sounds like your pre-build reading is kinda spotty. Step away from the tools and parts... slowly... and keep your hands where I can see them. Then go download http://www.ar15.com/content/manuals/FM23-9.pdf and read about what you want to do, starting around page 3-30. (PDF Pg. 101)
Notice the procedure is to use a barrel clamp, not a receiver clamp. If you're going to build something, a barrel clamp is a lot easier. Any upper receiver fixture takes a lot of reverse engineering and work to avoid coming up with something that is likely to damage the receiver. If you thought your main goal is to avoid marring the work, it's not. The fixture needs to distribute the stress to avoid bending the weaker areas. I made my own receiver block and barrel clamp and even if I count my time as worth $2/hr, it would have been cheaper to buy the tools. If you're good at reverse engineering, you just like to build things, and you accept that the tuition for your learning experience might be the price of another upper receiver, go for it. |
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Teeth are spread out. I see where you stated it was an old barrel...perhaps had been mounted/pulled before? You can still shoot it. Buddy of mine did the same thing (removed whole tooth) and he's had no problems. Before you pull it, take it out the range and shoot the piss out of it. See if anything's shifted afterwards. If not you'll be fine until you decide you need a new barrel. |
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rob, my OP was asking a torque rating which i was given, and if I had the wrong grease I'm sure someone would have chimed in by now. as far as hometown for teh block, i'll give that a try, i do plan to buy teh block in the next few weeks either way Just trying to save you some grief (and a cracked or warped upper). After you buy the materials, fit the block to your upper (filling internal space), you'll have spent more than what receiver block will run you (including cost for your time). Hell man, I've got one I could mail you. Made out of pine, looks like shit, and works about as well. |
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