Loose Handguard Cap - M&P15OR

[jmp45]

I know this has been covered for rail installs but I couldn't find anything about stock handguards. There's about a 1/32 inch of play in the cap with stock guards as well as moes. The rattle kind of annoys me. Is this normal and anything to be concerned about? Is there a fix? Thanks!

[Quib]

Rotational play, or fore and aft play?

[jmp45]

front cap, up and down, no rotation. The front cap is loose. There's a slight gap between cap and gas block. Maybe loosened up while breaking it in. I'm wondering if I could bend the bottom of the cap slightly just to tighten up the gap pushing forward to the gas block. I'm not doing anything though til I hear from you guys. Typically I break things before I fix them.. ;)

[Quib]

I’ve tightened up loose standard hand guards by shimming them inside the hand guard cap with thin strips of inner tube. Might be worth a shot.

Another idea along those same lines, is applying a bit of RTV to the inside of the hand guard cap. Apply a thin layer to the inside of the hand guard cap, let it cure, then do a trial fit. Repeat as necessary.

[jmp45]

Thanks Quib, worth a shot. But thinking about the way it moves, the guards are tight in the cap but the cap seems to have a bore cut at a larger diameter than the barrel. They may be typically loose on the barrel, but I didn't notice it when I put on the moes. It did the same thing with the stock guards before I changed them. I'll give your shim idea a try.. thanks again..

[Quib]

If the hand guard cap is extremely loose, then the shimming or RTV will be no help. Since your idea of loose may differ from my idea of loose, and I physically can not examine the weapon, you might want to give either of those suggestions a shot.

With the RTV you want to apply a layer to the inside of the hand guard cap in an attempt to create more fore and aft tension between the barrel nut and the hand guard cap.

[jmp45]

Thanks Quib, I think I came up with a temp fix.. the cap is loose between the gas block and barrel bevel that keeps the cap forward. Almost like the gas block wasn't seated back snug enough against the cap when they built this upper. I don't see how the block could move over time. I found some thin metal shim material and inserted from the bottom between the handguard cap and gas block. It's it tight fit so maybe it will hold, time will tell. The guards are back on and there's no play now. Thanks again Quib.

[Quib]

Sounds good. Hopefully the shim will stay put.

[M4Fundi]

What about rotational play of the handguards at the Delta Ring... any EZ fixes?