AR-15 front rail wiggle issue

[Horty]

I have a S&W M&P 15-X (It's the AR with the flat top and a half-rail that is not free floating) and the front rail wiggles a little bit is this normal? I never really noticed it until I put a foregrip on the gun and now I can really tell. It does not move much but maybe like 1/8 of an inch. It is really annoying, has anyone else had this issue and if so can it be fixed? Also will this afffect a scope if mounted on it and part of the mounting system is on the rail which moves? Thanks

 

[SMS]

It is normal for standard AR-15 style front handguards (rail or no rail) to move. It is not the preferred mounting point for optics...

If you want a stable mounting platform, get a free float.

 

[fishn&huntn]

Check the screws that hold the two pieces together if it has them.It will affect your zero to some point IMO.

 

[ez bake]

1/8" is a lot of movement - I'm not familiar with that particular rail, but I can't see where I'd be happy with 1/8" of movement when trying to hold a steady shot with a VFG - that would suck.

 

[Rob72]

It is normal for standard AR-15 style front handguards (rail or no rail) to move. It is not the preferred mounting point for optics...

If you want a stable mounting platform, get a free float.

That's pretty much it- get an ARMS or similar rail set-up, if you want accuracy and repeatability.

sigh...

however, you can take out vertical play by drilling & tapping the retaining lip for a pair of set-screws. I had one of the early Knights RAS mounts, and got tired of feeling like I had a pump action with a VFG mounted, so...

 

[Horty]

Can a good gunsmith fix the wiggle and if so who would you all recommend? How much does an ARMS or similar rail set-up cost?

 

[Rob72]

This is pretty average, in pricing. I have not tried the #50, that secures to the barrel nut, but ARMS stuff is top notch.

I would suggest posting a WTB, or (probably cheaper in the long run) watching the sale boards on the AR 15 forums. Someone parting out their rifle, or looking to switch to a piston or monolithic rail will be the best bet.

I can't recommend anyone to do the mod, since I've never seen anyone else do this, and I don't know how much lip your S&W rail has, but it can most likely be done using two 1/8" (3/16" if it really is that loose) 8-32 set screws. Drill and tap (using a forming tap) and either JB weld or Devcon metal epoxy. Brownells may have it a couple of bucks cheaper, but not much. KP is downtown, and good to deal with.

I'd suggest the metal epoxy if you really intend to keep the rail (vs selling it off unmolested), but JB weld is fine for what is essentially a non-load bearing area.

 

[grwd]

sounds like the op doesnt have a rail, but a top railed handguard. The slop is normal.

 

[Josh-L]

I thought the 15-X had a Troy rail on it? If it wiggles a little bit it's normal but if it moves a lot then you could of had one slip through that wasn't torqued properly and your barrel nut is loose.