View Full Version : Barrel Nut torque with Viking Tactics Extreme BattleRail
I installed a Viking Tactics 13" Extreme BattleRail this weekend. The directions say to torque the nut between 30 and 60 ft-lbs. The notch for my gas tube lined up just after 30 (maybe 31 or 32) but with this particular setup after you slide the rail on you turn the whole assemble back to the left an 1/8 turn or so, which makes it feel loose.
Everything seems tight after the set screws were tightened on the rail but I was just curious if this is normal/safe?
Jeremy45
You turn the barrel nut CCW after sliding the rail on :confused:
Doesn't that rail use a barrel nut similar to a USGI one? If you think you can get the next hole aligned without going over 60 ft-lb I would do that. Just do the tighten, loosen thing working it a bit further each time.
The notch for my gas tube lined up just after 30 (maybe 31 or 32) but with this particular setup after you slide the rail on you turn the whole assemble back to the left an 1/8 turn or so, which makes it feel loose. Jeremy45
Quiet-Matt
08-21-11, 19:44
Should be fine, the rail should feel loose untill the screws are tightened, but if you're actually turning the barrel nut that's bad. Like Eric D., I'm curious to know if you checked to see how much torque it took to get to the next notch.
Did you torque the barrel three times? Tighten, loosen...repeat three times. Don't use the torque wrench to break it loose though.
IIRC, you torque the barrel nut on, then slide the rail on and twist it until the tab hits the receiver, then torque the screws on the bottom of the rail when the upper rail is in alignment with the rail on the upper receiver.
The tab probably won't be in contact with your receiver when the upper rails are lined up.
Did you torque the barrel three times? Tighten, loosen...repeat three times. Don't use the torque wrench to break it loose though.
IIRC, you torque the barrel nut on, then slide the rail on and twist it until the tab hits the receiver, then torque the screws on the bottom of the rail when the upper rail is in alignment with the rail on the upper receiver.
The tab probably won't be in contact with your receiver when the upper rails are lined up.
That is exactly right on the install. I did tighten and loosen, went 30 loosened, 40 loosened all the way to 60 and the tab was right in the middle. I loosened all the way off and torqued to 30 then followed the install instructions. And yes you do turn the barrel nut counter clockwise to complete the install.
Interesting...I had the same alignment with the barrel nut supplied. 30#'s was lined up so I went to the next notch. I did have to continue to loosen and tighter with anti-seize until I hit my next slot at about 62#'s if I recall. That's strange how it would be in the middle at 60# with an alignment at 30#'s.
Post on my installation of barrel. (https://www.m4carbine.net/showthread.php?t=83333)
I hope you figure it out but I would shoot for the higher number.
And yes you do turn the barrel nut counter clockwise to complete the install.
This does not sound right. You tighten, torque and align the barrel nut, install the gas tube, and leave it alone after that. You turn the rail assembly counterclockwise as part of the install, but you do not turn the barrel nut at all once it has been aligned/torqued and the gas tube installed.
And yes you do turn the barrel nut counter clockwise to complete the install.
You should only be able to turn the rail on the barrel nut, just before you tighten the screws on the rail to lock it in. The barrel nut shouldn't move.
Your third torque value is, or should be, your final torque value, whatever that is to get aligned.
So if you tighten to 30, then 40, then 60, the barrel nut should be in its final posistion at 60ft lbs.
What kind of torque wrench are you using? Sometimes they aren't the most accurate thing ever, especially when using an AR-15 type wrench attatchment.
If you have to go past 60 ft lbs, you aren't going to destroy anything. If you hit 120 you are way too high. ;)
You can try another barrel nut if you are too far off. There are lapping tools, but that is almost another thread.
My choice would be to wipe the threads clean, regrease them, and just repeat the process. In all probability, you will end up past 60. Don't sweat it. The TM states not to go over 80ft lbs using the mil-spec wrench.
The important thing is you never loosen the nut to get alignment. You tighten to alignment.
Don't get hung up on the numbers. They aren't accurate. If this was some uber type precision shit, you would actually have to measure the offset of the wrench and calculate the final value for the torque. Wrenches are meant to be used with standard sockets, not AR15 barrel nut wrenches.
For the mechanically inclined I tend to say don't get wrapped up in torque values. In any case I would say to tighten the nut as close to the highest value as you can, while ensuring that the nut attains alignment.
The rail is what is supposed to be turned to complete the install, not the barrel nut.
I am using an off brand torque wrench that my dad bought a few years ago as this is the only thing I needed it for.
You slip the rail over after you torque the nut. It feels like the whole thing rotates counter clock wise but maybe it was just the rail. The rail has grooves that fit the nut so I don't see how they would turn independantly though
I am going to take it apart again and start over. Torquing to 60 3 time and will just align to the next notch if close. Will report back this evening.
You slip the rail over after you torque the nut. It feels like the whole thing rotates counter clock wise but maybe it was just the rail. The rail has grooves that fit the nut so I don't see how they would turn independantly though
It may feel like it, but it's not happening.
It may feel like it, but it's not happening.
OK, then it should be just fine where it is since I am at 30 ft lbs? Or would you still try again to get a higher torque value?
I installed a Viking Tactics 13" Extreme BattleRail this weekend. The directions say to torque the nut between 30 and 60 ft-lbs. The notch for my gas tube lined up just after 30 (maybe 31 or 32) but with this particular setup after you slide the rail on you turn the whole assemble back to the left an 1/8 turn or so, which makes it feel loose.
Everything seems tight after the set screws were tightened on the rail but I was just curious if this is normal/safe?
Jeremy45
Assuming the torque wrench is calibrated properly, 30 ft-lbs indicated is probably in the high 30's actual. Indicated torque is at the center of the drive. As soon as you add an extension (the Troy wrench), actual torque is increased.
Bookmark this calculator (http://www.belknaptools.com/extcalc.asp).
I am going to take it apart again and start over. Torquing to 60 3 time and will just align to the next notch if close. Will report back this evening.
I'd trend to the lower end. I've heard those barrel nuts are brittle hard.
Good link! The Troy wrench is real short from center of drive to center nut section. I would guess if he used a standard 12-14" Tq wrench he is at about 33#'s. Just my opinion but I would shoot for a higher value like I posted above. I'm no expert so take it as you wish.
Put torque wrench on at a right angle to the Troy wrench and you will get essentially the correct torque provided the Troy wrench is short in relation to the torque wrench. Works with any wrench/adapter that extends the effective length of the torque wrench (most anything but a regular socket).
It may feel like it, but it's not happening.
I took the rail off and looked at everything. Nut is still tight and there is a groove on the inside of the rail that lets it turn independent of the barrel nut. It's hard to turn and then it gives all of a sudden is why I thought it was the nut coming loose but I was mistaken.
Thanks everyone for your replies, after using to torque calculator and seeing everything is tight I left as is. I should be between 35 and 40 ft-lbs and everything feels solid.
Thanks again!!
Good link! The Troy wrench is real short from center of drive to center nut section. I would guess if he used a standard 12-14" Tq wrench he is at about 33#'s. Just my opinion but I would shoot for a higher value like I posted above. I'm no expert so take it as you wish.
I think it was about 18" but I don't have it next to me. 18" wrench plus 3 " extension set to 30ft-lb should be 35ft-lbs according to the calculator.
Assuming the torque wrench is calibrated properly, 30 ft-lbs indicated is probably in the high 30's actual. Indicated torque is at the center of the drive. As soon as you add an extension (the Troy wrench), actual torque is increased.
Bookmark this calculator (http://www.belknaptools.com/extcalc.asp).
Good link! The Troy wrench is real short from center of drive to center nut section. I would guess if he used a standard 12-14" Tq wrench he is at about 33#'s. Just my opinion but I would shoot for a higher value like I posted above. I'm no expert so take it as you wish.
I think that issue was corrected and it happened only with a few batches. I may be wrong about that.
I'd trend to the lower end. I've heard those barrel nuts are brittle hard.
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