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Posted: 1/13/2015 12:49:01 AM EDT
I have a Head Down Provectus 9" free float rail installed on my rifle. I followed the instructions to a 'T' when I was installing it, but now after shooting it a few times I've noticed that I have a tiny amount of left to right rotation in the rail. It kind of feels like the barrel nut is loose but the gas tube is preventing it from rotating too far. I'm sure that I'm going to have to pull it apart and try to tighten it back up, but I was wondering if anyone else has run into this problem with their rails. See pic of actual rail and nut below:
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If the barrel nut is rotating, then you did not install it correctly.
Lighlty moly grease lube the threads of both the nut and barrel socket, and the front of the barrel extension where it will make contact to the inside of the barrel nut. If you need moly lube, Brake grease in the little packets at the counter of any auto parts store. Take the barrel nut to 30ft lbs, back it off, take it to 30ft lbs and back it off a second time (this will help mate the threads to each other and inside of the nut to the front of the barrel extension bearing surface), then take the barrel nut up to 35fts, then take it the needed amount more to center the top channel in the nut to the upper receiver gas tube channel without going over 80ftlbs. If you are click off at 80 ftlbs, before the barrel nut top channel indexes correctly with the receiver gas tube channel, back off the barrel nut and re-torque again (may take a time or two for the threads to mate enough to allow such, or just use the shims that come in the kit instead). So barrel nut needs to be installed at +35ft lbs with all the parts greased to get a true reading, but do not go over 80 or you will crack or bend the upper receiver socket on the receiver. Also, max reading is really 85ftlbs, but unless you are dead squared with the receiver with the wrench, you can end up over torquing to the side and bending the upper barrel socket against the receiver center line. Also to point out, blue loctite (242) on the tube to barrel nut bolts goes a long way to make sure that they stay tight, and allow them to be removed later down the road. If you use red loctite (272), then to remove the bolts without stripping the bolt head out with a wrench, you will need to heat transfer( old wrench in the heads and heat up the wrench with a torque until is glows/ you smell a sweet smell) to first break down the loctite bond before you go to removed the bolts. |
| Couldn't have said it better. Do you have a vice block? If you're just doing it by hand, you aren't going to get the proper amount of torque required to have it installed properly. I too have a 15" rail from them and after heavy use, it's still on snug. My only issue with it is the crappy mounting screws that keep rusting. I have Head Down ship me new screws and they too have began to rust. Not enough to bother me, just might dab some lube on the faces of the screws to prevent anymore corrosion. |
| I have three of these rails, haven't had that problem. The anti-rotation tabs located where the top of the handguard meets the upper receiver should be stopping any rotation. As the previous post said, start with mating the threads properly. My rails all included shims to use in the event that the gas tube hole would not line up under the correct torque. Those are of various thicknesses, so a little experimentation may be required to find the proper shim. |
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