I have a keymod handguard on one of my ARs which I installed a ARCA rail onto. After two dozen shots or so, it loosens up. I torque the bolts (there are 4 of them) to 15 in.-lbs. Should I locktite the bolts to stop them from loosening? I can torque to 20 in.-lbs. but as these are only 8-32 bolts, this may be too much.
KeyMod Bolt Torque
- Thread starter MMH
- Start date
Degrease and blue loktite.
Push the attached accessory in the direction opposite the recoil force as you tighten.
I've always torqued keymod to 20 in-lb.
Push the attached accessory in the direction opposite the recoil force as you tighten.
I've always torqued keymod to 20 in-lb.
Simple, use the loktite to fill the gap between the two parts. If the fit between the two parts is tight, the loktite will cure and can provide some adhesion between the two pieces together.
BCM recommends no more than 18-20 in/lbs of torque and blue loctite for their KeyMod accessories.
it must depend on the accessory. I’ve got some rail mounts that say 30 in/lbs on the package
I’ve noticed that both Keymod and MLOK mounts/rails/accessories have come loose on multiple platforms in my DM courses, all of which were either Blue or Red Loc-tited.
I had a talk with a buddy of mine about it who is an engineer, gunsmith, works with a lot of exotic alloys, stress fracture analyses from laser welding, things like that, very cerebral and down-to-earth too.
His take was that since those Loc-tite compounds are polymers, they go into a liquid state under long strings of fire where radiant heat causes them to convert from a more solid state.
I had a talk with a buddy of mine about it who is an engineer, gunsmith, works with a lot of exotic alloys, stress fracture analyses from laser welding, things like that, very cerebral and down-to-earth too.
His take was that since those Loc-tite compounds are polymers, they go into a liquid state under long strings of fire where radiant heat causes them to convert from a more solid state.
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You're right, my bad, I think that 18-20 is mostly for polymer accessories, aluminum looks like it goes up to 30 in/lbs.
If you're getting your accessory mounting points to 350-400° F, you've got bigger things to worry about beyond loosening srews.
I don’t think you need to get that high in temp to cause thermal expansion of the Loc-tite. From a normal heat cycle, once it contracts, we think it might be losing its torque spec at that point. A lot of my courses are in the middle of the winter, well below freezing, or wide temp swings on spring days where it goes from really cold in the morning, to really hot in the day, back down to really cold for the night portions. Combined with constant winds, there’s a lot of thermal gradient/temp range for the extra parts to find a way to come loose.
I purposely schedule cold weather DM and LR courses in the dead of winter. They end up being as much of a gear shake-out as a skills-building challenge in those conditions, but leave you with a sense of how you and your gear will actually fair.
I’ve never relied on KeyMod or MLOK to secure lights/lasers, but have just seen this across several different rifles now over the years. Based on what I’ve seen, I won’t trust either mounting method for lights/lasers.
I purposely schedule cold weather DM and LR courses in the dead of winter. They end up being as much of a gear shake-out as a skills-building challenge in those conditions, but leave you with a sense of how you and your gear will actually fair.
I’ve never relied on KeyMod or MLOK to secure lights/lasers, but have just seen this across several different rifles now over the years. Based on what I’ve seen, I won’t trust either mounting method for lights/lasers.
I’ve found myself just using the fixed 12 o’clock rails, as well as handguards with the small rail sections up front at at 3, 6, 9.
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