I recently switched to a free float rail on my Colt 6920 that bolts on by two lower bolts on the rail that tighten around the barrel nut.
The problem I’m having is that the rail seems to work itself loose no matter how I much I tighten it down.
I was looking for an alternate way to secure this rail to the barrel nut so that it won’t slip forward off of it.
The rail seems to pop-off on average after every 100 rounds fired suppressed or unsuppressed.
Any suggestions would be greatly appreciated.
If this is a Midwest gen2, which it appears to be, the barrel nut has its teeth at the rear (receiver) end, not the front like a GI barrel nut. The rail slips over the nut but only two tiny little prongs go over the nut-teeth to prevent rotation. The top of the rail should be nearly touching the receiver (there may be a gap but it should be in .01" range).
I’ve used two of the SS gen2 rails, with the same attachment system, for quite a while without problems. However, there have been other people reporting that the rail slips off, countered by a few trainers reporting they’ve put the thing through hell without a problem. I see the vertical grip on your rail - if you are pushing forward on that, it’s possible that this rail is just not going to work for you. Here’s what I would try first:
-remove the rail and degrease the barrel nut and inside of the rail where it mates.
-put some loctite on the scored area of the nut, reinstall the rail, put some loctite on the clamping botls, tighten bolts to the torque spec
Midwest has a rep on this forum and you could also contact them for help.
If you have watched the development of the MI SS handguards, they have improved the barrel nut, and stated clearly in the instructions that you need to Loc-tite the handguard to the barrel nut once it is correctly indexed.
The older barrel nuts have a smooth cylindrical surface ahead of the teeth, whereas the new ones have a knurled surface to address this problem.
I have seen non Loc-tited versions slip off like this in my DM Course, while Loc-tited ones have stayed put in high volume CQM courses without a hitch.
I’m taking my AR to the local gunsmith that originally mounted the rail for me and see if degreasing the barrel nut and loctite-ing it will help.
For those that have mentioned it, Yes this is the MI Gen 2 T10 with the improved barrel nut that has the knurled surface.
I was still surprised to find that the inside of the rail that mates up with the barrel nut has a smooth-slick surface, that doesn’t seem like a great match.
This why BCM mounts the KMR rails the way they do with the pinch bolts at the top. Pinch bolts at the bottom spread the extrusion at the top. Gluing it on with Loc-Tite is the ultimate bandaid!
Now come on now… Midwest has taken a bashing for years. They’ve been steadily improving. I own and have owned some very nice, top-dollar rails (URX, Geiselle, DD, Noveske) and the MIs are just fine. Any of their newer released rails should be GTG.
But you’ve got to give them credit for at least using their own barrel nut on the SS series. I did vibra-tite mine and it is very difficult to induce flex on the rail. For a lightweight and inexpensive option on a plinker or a loaner for if the SHTF they’re great. On my personal SHTF rifle I’m sticking with DD or KAC. I have no qualms with recommending the SS and SSK series rails at least.
Its not simply Loctite. It is green retaining compound that is supposed to be used and it comes with the rail. Make sure you do proper preparation first.
