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Torque specs picatinny rail to receiver

chopper_man

chopper_man

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Hey all,

Got a Mossberg Night Train 3 in .308, it's essentially an ATR-100 with scope and bipod package. The picatinny rail came loose on it, doesn't look like any lock-tite was used from the factory. I gave Mossberg customer service a call and they said it's 8 foot pounds of torque, I confirmed with the guy saying are you sure your not reading inch pounds because 8 foot pound's (96 inch pounds) is huge for a 6-40 screw. I asked again to confirm it and he said yes, it's right there in his document. I said thanks and ended the call.

What's everyones thoughts on this? I think if I try and go up that high I'm going to snap the heads right off these suckers or worse, strip out the holes. A ton of searches show anywhere from 15-65 inch pounds with the lower side being used on aluminum receivers, mine is steel. I really don't trust the answer I got from Mossberg.

Thanks all!
-Brian
 
my rem 700 base is only 15 in-lbs. snug and a light pull with blue locktite should be fine if you dont have a torque wrench
 
Tighten until it strips, than back off 1/2 turn [wink]


My search for a 6-40 steel screw is only 12 inch pounds. Put some loc-tite on the threads, and crank it down.

Is it an allen cap screw? Somebody once told me that a standard sized 'L' shaped allen wrench is made so its nearly impossible to apply too much torque given the size of the wrench for the size of the screw it fits. The only allen wrenches I have are shaped like a '7' so I've never been able to confirm or deny that.
 
I share the OP's skepticism. According to the engineers' Pocket Reference, the standard dry torque specification for a 6 x 40 Grade 5 screw is 1.49 ft.-lb., which equates to 23.84 in.-lbs.

I don't recall ever looking this up before seeing this thread, but I guess I must have, for my standard for these screws in this context has always been 21-24 in.-lb.

Edit: for 8 x 36 screws, the specification is 2.57 ft.-lb (41.12 in.-lb.).
 
Last edited:
Thanks for everyones input. I tried Mossberg again today and was told that they have no specs on that. Wonderful..... I think I'm going to shoot for 20 inch pound wet (with the loctite) which should put me in the dry range of 24 or so.
 
In regards to #6 screws: they are the weakest American Standard size screws in the line-up if you plot shear strength vs. cross-sectional area.
 
chopper_man said:
Hey all,

Got a Mossberg Night Train 3 in .308, it's essentially an ATR-100 with scope and bipod package. The picatinny rail came loose on it, doesn't look like any lock-tite was used from the factory. I gave Mossberg customer service a call and they said it's 8 foot pounds of torque, I confirmed with the guy saying are you sure your not reading inch pounds because 8 foot pound's (96 inch pounds) is huge for a 6-40 screw. I asked again to confirm it and he said yes, it's right there in his document. I said thanks and ended the call.

What's everyones thoughts on this? I think if I try and go up that high I'm going to snap the heads right off these suckers or worse, strip out the holes. A ton of searches show anywhere from 15-65 inch pounds with the lower side being used on aluminum receivers, mine is steel. I really don't trust the answer I got from Mossberg.

Thanks all!
-Brian
Click to expand...
I tried 30 in lbs and stripped the screws. Looks up specs on some another area, "scope mounting" said 13 in lbs. I went with that, it seems to be holding OK.
 
chopper_man said:
Hey all,

Got a Mossberg Night Train 3 in .308, it's essentially an ATR-100 with scope and bipod package. The picatinny rail came loose on it, doesn't look like any lock-tite was used from the factory. I gave Mossberg customer service a call and they said it's 8 foot pounds of torque, I confirmed with the guy saying are you sure your not reading inch pounds because 8 foot pound's (96 inch pounds) is huge for a 6-40 screw. I asked again to confirm it and he said yes, it's right there in his document. I said thanks and ended the call.

What's everyones thoughts on this? I think if I try and go up that high I'm going to snap the heads right off these suckers or worse, strip out the holes. A ton of searches show anywhere from 15-65 inch pounds with the lower side being used on aluminum receivers, mine is steel. I really don't trust the answer I got from Mossberg.

Thanks all!
-Brian
Click to expand...
obviously what you ask depends upon size of screws that you use.
65 is insane and can be a torque to attach a receiver to the chassis. an 18 for smaller screws, a 20-25 top for bigger ones is ok. i use 20 for rails. proper ones come with blue loctite already on them, if not, do not forget to put some on. if it is a wet locktite - set torque lower, to 18 or so. 20 should be fine too.
some extra chineseum screws may not even survive that.

and - a must have thing:
www.ebay.com

Wheeler Manual Firearms Accurizing Torque Wrench with Inch/Pounds Measurement | eBay

EASE OF USE: Apply, repeatable, accurate torque settings to scope rings, guard screws, windage screws and base screws, which aids in accuracy and decreases the opportunity for problems in the field. INCLUDES: 10 bits (hex to square adapter, #10 flat blade, #32 flat blade, #11 flat blade, 5/32...
www.ebay.com
 
another one post wonder necrothreading on NES.... although in all fairness it happens on almost every forum I read.
 

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