Looking to mount a vertical grip to a standard handguard on a carbine AR-15. This is my first time, so I'm unsure of what grip to buy and where to find a rail to fit underneath a standard handguard, non quad rail.

I've heard that Tango Down makes a very good grip, but they fit tight and are a bear to mount.  Will they cause movement in the lower half of the handguard?  Any other suggestions?  I've read that KAC is a good grip.  Would that fit as tight?  Where can I obtain a KAC? hanks.

AAC and GG&G make nice rails.I have one for sale and I'll throw in a free VG that mounts with screw through a slot.   http://www.advanced-armament.com/products/ar15.asp         Here's the link to AAC.

Here's one 6" rail that fits to a standard handguard: Universal Rail  You can find it at ACE Ltd, scroll down about 4/5's of the page.

Since your handguards aren't fixed you will get some movement if you twist the rail left/right.  How much movement depends on how tightly your handguards are fitted.

I have an SOG vert grip with a Surefire 6p and tape switch care of Brightflashlights mounted to a GG&G rail.  My only problem is that there is barely enough room for both of them.   Be sure that you have enough rail real estate if you decide to go with a handguard-mounted rail system.

For the record, yes, there is some movement in the vertical grip, certainly more than if I had removed the handguards and gotten a nicer rail system.  But for the money, and for the extremely small amount of movement, it is worth it.

My .02

I read on here a while back that someone used jb weld on the end
of the hand guards to tighten them up. If you did'nt like it you could
file it off. Might be a cheap fix.

To tighten up the hand guards just fold a small piece of paper and insert it in the groove at the back of the hand guard that fits over the barrel nut. When I say small that's what I mean. It doesn't take much. Install the handguards by squeezing then together at the back and work the slip ring back over the handguards. I have used this method on an M-16 with Beta-C mag. This rifle gets extremely hot and I haven't had ANY problems. I think you will be pleased with the results and it doesn't cost anything to try it.

Rats