Am I Overthinking This?

[Bullwinkle]

I can see the light at the end of the tunnel with respect to my LR-308 build (the rifle itself, that is, not necessarily the final finished package with accessories & upgrades), but I have this one nagging problem that I just can't seem to shake; and that problem is, how to mount a rail--or just a couple swivel/bipod studs--to a carbon fiber free-float tube.

I've heard from some of the wonderful, helpful folks here on CalGuns that carbon fiber needs reinforcing, or it'll start shredding at the bipod stud mount over time under recoil.

I've looked online, and I can't find any sort of product for reinforcing the tube.

I've contacted DPMS directly and asked them for their advice on how I should proceed, and their somewhat snide response was, "We just drill a hole, tap it, and then go shoot the rifle."

Also, the more I've thought about this as I've been doing my searching, it seems to me that there has to be an inherent problem with mounting a flat rail (and flat nut) on a round piece of tubing... regardless of whether it's made from carbon fiber, aluminum, or whatever. Torque the mounting screw/nut too much and the tube cracks/deforms under pressure as the flats compress.

So what I "believe" I need is a shim/adapter that is flat on one side and radiused on the other... both for the inside and outside diameters of the tube. That way when I tighten the mounting screws, the rail & nut are on the flat faces of the shim, while the handguard is compressed/reinforced between the inner & outer radiused faces.

So... what's the scoop, am I being OCD whacko about this? Are there any shims such as I've just described available of which anyone is aware? Or am I just overthinking a problem that doesn't exist and should take DPMS's advice and drill/tap/mount directly to the carbon fiber tube?

As always, thanks again for all your help and any suggestions!!!

[john323]

Radius the bottom of your rail to match the tube then use bedding compound around the screw hole. Make sure you use a good release agent on the screw. A small piece of shim stock will serve as a flexible washer inside the tube.

[LOW2000]

Or you could bend a washer.

[wash]

Get the back side of your rail radiused slightly smaller than the radius of the tube (so it bears on the outer edges) and make backing plates to go inside the tube and hold the threads that your rail and bipod stud attach to.