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Posted: 12/11/2015 6:49:41 PM EDT
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I put a 14" keymod rev 2 on and I can't get it centered to the barrel.
I've used several LaRue and Troy Vtac handguards and have never hade any problems getting things lined up. The barrel nut is a plane milspec nut, no visible marks ect. I tightened the screws in a cross pattern. Any ideas? |
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I had the same issue with mine. When I tightened it down as evenly as possible it was always pulled off to one side and was crooked. If I held it in place, perfectly centered and tightened it down, you could press on the end of the rail and it would move and stay wherever it was pushed.
I tried multiple barrel nuts from quality companies(Rainier,BCM and Colt) but nothing changed. I took it to a local AR manufacturer and they even tried machining the top of the part that clamps down in an attempt to fix it but it didn't help. I eventually got a replacement from Fortis but by that point I had enough of screwing with it and sold it. The guy never complained so maybe the new one worked for him. I on the other hand found my way to the SLR Rifleworks website and picked up a 15" SOLO and couldn't be happier. No more rails that use factory barrel nuts for me... |
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Quoted:
I had the same issue with mine. When I tightened it down as evenly as possible it was always pulled off to one side and was crooked. If I held it in place, perfectly centered and tightened it down, you could press on the end of the rail and it would move and stay wherever it was pushed. I tried multiple barrel nuts from quality companies(Rainier,BCM and Colt) but nothing changed. I took it to a local AR manufacturer and they even tried machining the top of the part that clamps down in an attempt to fix it but it didn't help. I eventually got a replacement from Fortis but by that point I had enough of screwing with it and sold it. The guy never complained so maybe the new one worked for him. I on the other hand found my way to the SLR Rifleworks website and picked up a 15" SOLO and couldn't be happier. No more rails that use factory barrel nuts for me... You just described what mine does. 
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I have that rail too only mine is the M-Lok flavor.
I love it. But it can be a bear to center due to the design. Do you have a picatinny rail, one piece scope mount, or something similar? If you did, you can "bridge the gap" with the upper receiver and handguard, then do your final tightening on the handguard screws underneath. If not, my best recommendation would be to take baby steps during your tightening. I don't necessarily use a criss-cross. I kind of just watched the gap on either side while tightening, and would barely turn a little here, then barely turn a little there, until both gaps were close to the same. Keep in mind I do understand where you're coming from. I probably took this rail off a dozen times in order to barely tweak the barrel nut timing. It's just the nature of the design. Slight variances in uppers, barrel nuts, torque, etc. all seem to have a magnified effect on these things. Take your time and don't get frustrated. Like I say, I probably did it a dozen times until I was satisfied. ETA: Also, I used my free hand to physically hold or push the rail tightly against the upper while tightening the screws with the other hand. If you don't do this and tighten there is no telling where the thing will wind up. |
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I used the scope mount bridge method and it helped, but I still can move it off of center. I put buis on so I'll sight them in and see if I can shift the poi. If I can I'll be returning it. Thanks for trying though. Understood. I don't want to recommend what's not recommended by the manufacturer but I'm going to anyway. Mine is rock solid. I also overtightened the screws. I'm not recommending a breaker bar or anything, but I did use more torque than what's recommended. Yes, I can physically push mine on the very end and move it some, but I can do that with any rail on the market. It shouldn't move much even with strong pressure, and when it does it should spring right back in place. If yours is moving off center and "sticking" into that off center position, try snugging the screws up some more. If that doesn't work, you may need a replacement. Hope this helps. ETA: Here's a super shitty video that I took trying to show you what I'm talking about. Please ignore all of the bullshit you might see on my workbench. 
super shitty video |
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Thank you for the replies. I tightened the rail until there is no gap from top to the bottom clamp. I'm going to start pulling the stainless
screw inserts if I go tighter. If worse comes to worse I can remove some of the material from the bottom clamp and run longer screws/nuts to through bolt it. I have this on a pinned 14.5 barrel, so I've screwed myself there. I didn't want a proprietary nut/handguard setup. I can move it and it still stays off center. Like the other posts state, I expect them to move, just not stay that way. Lesson learned. |
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Quoted:
Thank you for the replies. I tightened the rail until there is no gap from top to the bottom clamp. I'm going to start pulling the stainless screw inserts if I go tighter. If worse comes to worse I can remove some of the material from the bottom clamp and run longer screws/nuts to through bolt it. I have this on a pinned 14.5 barrel, so I've screwed myself there. I didn't want a proprietary nut/handguard setup. I can move it and it still stays off center. Like the other posts state, I expect them to move, just not stay that way. Lesson learned. Man, that sucks. I hate to hear that. 
Especially with the pinned muzzle. There should be a gap of some kind. If it it's still doing what you're talking about there is definitely a defect or issue. Mine is not even that tight. I've been real happy with mine. But I was scared of this happening to me. Probably harder to guarantee fit on rails that use the standard nuts. Please contact Fortis and let us know what they say. |
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