Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login
Site Notices
9/22/2017 12:11:25 AM
Posted: 9/17/2005 12:16:06 PM EDT
I just installed my Larue FFHandguard on my Mid length...the problem I am having is that when I torque it to the recommended 30ftlbs....it lines up the perfect hole on the barrel nut with the gas tube...then the problem is that after installation I went out to shoot it and torqued the vertical handle hard and it loosened the barrel nut...

SO..i went back and tightened it to the 30ft.lbs hole and then turned it to the next one....which was real tight.....REALLY TIGHT...over 110ftlbs(or more) according to my torque wrench...

Is that safe on my receiver?...at that tightness I dont need that antirotational feature he has on it.


The next problem is that the antirotational piece has a lot of play...side to side and front to back....the notches are not tight up against the receiver and when I twisted the handguard loose it helped stop the turn to save my gas tube but I figured that if the piece is tight on both sides of the reciever that it would prevent any degree of rotation and thus would not matter if the barrel nut was torqued to 15ftlbs or even 120ftlbs....

any thought>?
thanks!
Link Posted: 9/17/2005 12:20:02 PM EDT

Originally Posted By drabchoi:

The next problem is that the antirotational piece has a lot of play...side to side and front to back....the notches are not tight up against the receiver and when I twisted the handguard loose it helped stop the turn to save my gas tube but I figured that if the piece is tight on both sides of the reciever that it would prevent any degree of rotation and thus would not matter if the barrel nut was torqued to 15ftlbs or even 120ftlbs....

any thought>?
thanks!



I, for one, wish that Larue did not design the locking plate to work with the lowest common denominator out of spec receiver. At least include one that will fit tight with a CMT/Colt receiver and another for the defghijklmnop, etc. brands. It can't be an expensive piece...
Link Posted: 9/17/2005 2:43:27 PM EDT

Originally Posted By drabchoi:
I just installed my Larue FFHandguard on my Mid length...the problem I am having is that when I torque it to the recommended 30ftlbs....it lines up the perfect hole on the barrel nut with the gas tube...then the problem is that after installation I went out to shoot it and torqued the vertical handle hard and it loosened the barrel nut...



When I installed my LaRue, 30# lined it up perfectly. I also use a vertical grip and have never had any problems, and it's on a full-auto Colt carbine. Like Sovereign mentioned above, LaRue used to make a locking plate that fit very tightly, but started receiving complaints from owners of out-of-spec uppers, so they increased the clearances a little so that they would fit ALL uppers.

Did you use moly lube on your upper receiver's threads so that you would get an accurate torque reading? You might try loosening and tightening the barrel nut numerous times to seat it before giving it the final torquing. This should lower your overall torque reading enough to get you in the 30-80# spec.
Link Posted: 9/17/2005 5:18:50 PM EDT
I used moly lube...the torque difference from 30 to 100+ is from the perfect hole to the one next to it. HOw would tightening and loosening it reduce torque value? I assume that since I got it set up now not to mess with it....

Its so tight now, who needs the antirotational piece.???

If you know which direction to turn it to loosen it while your holding the rifle....30ftlbs is not enough pressure to keep it from loosening when you twist a verticle handle hard enough.
Pretend your're in the sandbox kicking down a door and grab that rifle tight and I bet you'll be able to twist the barrel nut loose.....I did it and lost my zero... Not a good option for me if I get in a tactical situation or even going to carbine class 6 hours away with no tools.
Link Posted: 9/18/2005 6:32:43 AM EDT

Originally Posted By drabchoi:
How would tightening and loosening it reduce torque value?



I personally have no scientific reason for why it works (although I'm sure that there is one), but it really does work.


Pretend you're in the sandbox kicking down a door and grab that rifle tight and I bet you'll be able to twist the barrel nut loose.....I did it and lost my zero... Not a good option for me if I get in a tactical situation or even going to carbine class 6 hours away with no tools.


I can't explain your situation, but I've seen cases here on Arfcom of guys actually going LESS than 30# with no detrimental effects. In armorer's class we were taught to stop at 30# if it lined up correctly, and this is considering the rifles will be used in life-threatening situations.

I'd say that you might as well leave your rifle like it is, as it is already put together and seems to function okay. If there had been any damage done, there'd be no way to reverse it now anyway.


Link Posted: 9/18/2005 3:20:09 PM EDT
thanks for the advise....try to humor me and torque that vetical grip and see if you can loosen your barrel nut...30ft.lbs really isnt that much...If i wasnt using a grip and was just using the handguard itself there is not way I would be able to loosen it.. I called Larue and some one there feels a little more comfortable with a value a little greater than 30....oh well
Link Posted: 9/18/2005 5:02:49 PM EDT
The threads on both the barrel nut and receiver are not completely smooth and straight out of the box. By re-tightening the barrel nut, this causes the threads to smooth and straighten out. This is generally termed seating the threads and the difference in torque can be quite pronounced with re-tightening when dealing with barrel nuts and receivers made out of aluminum. There is a reason the mil. TM recommends that the barrel nut be re-tightened three times.
Link Posted: 9/18/2005 5:07:37 PM EDT
Thanks for clearing that up...I assume the not so sure aluminum and annodizing on the threading may not be perfect. I guess mine will never come apart now unless you hang off the barrel nut wrench...
Link Posted: 9/18/2005 9:16:06 PM EDT
I don't see this asked or discussed much when the issue of torque comes up but are you using your torque wrench at a 90 degree angle to your barrel wrench or as a straight extension of it? I just recently had a long time engineer acquaintance install a barrel nut with the same results as you with 30 ft. lbs. lining things up perfectly which he was very concerned about being tight enough. After I witnessed his installation procedure I showed him that the actual torque calculated to only 25.3 ft. lbs. with the barrel wrench used as an extension of the torque wrench.
Link Posted: 9/18/2005 10:40:16 PM EDT
airswift is right with any type of extension to a torque wrench the readings will not be true.


i always torque a little extra since the 30# is the min. for the bbl. nut.
Link Posted: 9/19/2005 3:46:36 AM EDT
Thanks for an interesting point,....I use my Sears torque wrench with my DPMS multitool which fits perfectly by the way...(since people are saying they are out of spec). I dont know how else to torque it down...I guess that may account for some error. I am not sure whether doing it that way accounts for the error being higher than normal reading or the opposite.
Top Top