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Posted: 2/19/2009 3:54:47 AM EDT
| I was installing my barrel, using moly grease on the upper, I tightened 3 times then got tight with the final snug, and I was 1/4 of the way on to a new hole. So...do i back it off the 1/4 hole and go with that one, or crank the final 3/4ths of the hole I'm on to align? Well, i opted to crank and I snapped the damn stud off my dpms barrel wrench. Needless to say, I'm pissed. It was definately a super tight fit, but if I had backed off to the previous hole, then I'da been too loose. Is dpms good about replacing their tools, or am I outta luck. Now I have to order a new wrench and wait to finish the build, but I'm worried it might happen again. Surely I'm not the first to run into this problem. Also, any suggestions on a better wrench/tool?? Thanks in advance. |
| I know this isnt what you want to hear but you may have to grind a tooth off. I had the same problem installing a Bushmaster barrel It wouldnt index and if i backed it off it was loose. I ended up grinding a tooth off, It worked. Ive put on hundreds of barrels and it dosent happen very often where they wont index. |
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Quoted:
I was installing my barrel, using moly grease on the upper, I tightened 3 times then got tight with the final snug, and I was 1/4 of the way on to a new hole. So...do i back it off the 1/4 hole and go with that one, or crank the final 3/4ths of the hole I'm on to align? Well, i opted to crank and I snapped the damn stud off my dpms barrel wrench. Needless to say, I'm pissed. It was definately a super tight fit, but if I had backed off to the previous hole, then I'da been too loose. Is dpms good about replacing their tools, or am I outta luck. Now I have to order a new wrench and wait to finish the build, but I'm worried it might happen again. Surely I'm not the first to run into this problem. Also, any suggestions on a better wrench/tool?? Thanks in advance. On the barrel nut deal you can back off and tighten more then 3 times to sneak the barrel nut into time. On the wrench. I've snapped the DPMS wrench too. I drilled it out and pressed in a 3/16" stainless pin. |
| Great ideas from both of you. Thanks! I ended up drilling out the broken stud and stuck my steel 3/32 punch thru the hole and got my barrel nut back off. Worked pretty darn good. now I guess I have alot of back and forth tightening and loosening to get to that next hole. Sure seems like a long way to go! Thanks guys! |
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Quoted:
I know this isnt what you want to hear but you may have to grind a tooth off. I had the same problem installing a Bushmaster barrel It wouldnt index and if i backed it off it was loose. I ended up grinding a tooth off, It worked. Ive put on hundreds of barrels and it dosent happen very often where they wont index. No don't do this! Grinding a tooth off the barrel nut is just not a good idea. Either try a different barrel nut or use shims. |
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You did not mention the use of a torque wrench...but you really should be using one. I have the DPMS wrench and have never broken a pin off of it so that tells me (barring a defective wrench) that you are over tightening your barrel nut.
The torque spec on the barrel nut is - 30 Ft. lbs. Minimum, not to exceed 80 Ft. Lbs. to align the next slot in the barrel nut. What you need to do is use a torque wrench with your barrel wrench and torque the barrel nut to 30 ft. lbs. 3 times to seat the threads. Then set the torque wrench to 80 Ft. lbs. and turn it till the hole is indexed properly. When done this way you should not exceed 80 Ft. lbs. of torque and the nut will be sufficiently tight. The reason that the torque specs are so broad 30-80 is so you can index the nut. Hope this helps. |
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Quoted:
Great ideas from both of you. Thanks! I ended up drilling out the broken stud and stuck my steel 3/32 punch thru the hole and got my barrel nut back off. Worked pretty darn good. now I guess I have alot of back and forth tightening and loosening to get to that next hole. Sure seems like a long way to go! Thanks guys! Thanks. I'll definitely check this out. My dpms wrench only had 2 studs. 3 seems much better, and I've never seen a 5. That sounds like the proper way to go. Also, I was tightening a larue nut, so I didn't want to cut out a tooth. I also think I had to have been over torquing, but when I got snug after the 3 turns, I wasn't really using much force, and i was a quarter way on to the next hole, so I figured I must make it to the next one, but that sucker wouldn't budge much more. However, after rewatching the 2 videos on Brownells and Larue's websites, I had to have been over torquing. They both make it look like there's nothing to it. |
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Quoted:
You did not mention the use of a torque wrench...but you really should be using one. I have the DPMS wrench and have never broken a pin off of it so that tells me (barring a defective wrench) that you are over tightening your barrel nut. The torque spec on the barrel nut is - 30 Ft. lbs. Minimum, not to exceed 80 Ft. Lbs. to align the next slot in the barrel nut. What you need to do is use a torque wrench with your barrel wrench and torque the barrel nut to 30 ft. lbs. 3 times to seat the threads. Then set the torque wrench to 80 Ft. lbs. and turn it till the hole is indexed properly. When done this way you should not exceed 80 Ft. lbs. of torque and the nut will be sufficiently tight. The reason that the torque specs are so broad 30-80 is so you can index the nut. Hope this helps. +1 This And get a cheap GI armorer's wrench from Brownells (with square recess for use with a torque wrench). It's the one that is rectangular in shape with no "handle". After close to a dozen builds and several that were torqued into the 60-80ft-lb range, never a problem. Three times tightening and loosening is just the minimum best practice, do it as many times as necessary so you can sneak the barrel nut to the next notch. |
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Three times tightening and loosening is just the minimum best practice, do it as many times as necessary so you can sneak the barrel nut to the next notch. This is the ticket, along with plenty of grease. You can use a torque wrench if you wish, but I personally feel for this application, they are unnecessary. |
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Here's my new modified barrel wrench!
http://img.photobucket.com/albums/v491/wqcustom/Feb202009004.jpg |
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Here's my new modified barrel wrench! http://img.photobucket.com/albums/v491/wqcustom/Feb202009004.jpg Looks like the other pin is a little bent too. 
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remember this forum is open to public and you are choosing to listen to some gun nut's unverified opinion!
M(very)HO, remove everything, including grease, let stand for 24hr (hardest part). GENTLY, Hand fit it; no tools, no vise, no wrench. You are looking for the hole alighnment or for something out of whack. Clean everything again as to remove resedues/ encumbrances from thread path (airhose is a great help with this. Hand fit it again looking for any variances. Then follow ar15.com assembly procedure. if it still is not square, repost and ignore me. I try to assemble with my own power (liberal use of power) to check fit. also always protect threads w/ barrel nut or similar. |
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