A couple of months ago while cruising through a local gunshow, I spotted a vertical foregrip that had an interesting configuation. It really fit my hand well. At about $20.00, it's worth a try. It works really well. I even got a couple for some friends of mine. Brand name is UTG and of course, made in China.
Others that I work with asked me to find more. In doing so, I discover that they are made for the dreaded AIRSOFT rifles. HOLY CRAP!!
Yes, I know I have committed a grievous sin even if not on intentionally.
So I take this grip and literally beat it with a hammer. It still hangs in there with no
problems. Hundreds of rounds on an SBR, still OK.
Has anyone else used this grip. If so, your secret is safe with us!!

I have the same grip on my patrol rifle.  Locks up tight.  I have had no problems with it so far.  A few buddies who have tango down VG like the feel of mine better!  Price I paid = 19.95...

http://i110.photobucket.com/albums/n82/merky525/Ar15.jpg

Brownell's sells it as the TAPCO Deluxe ergonomic vertical grip.

Picked up two of them and I an pretty pleased.

It has pressure switch pockets on each side, and holds 3 CR123 batteries if you want it too.

I have one on my latest build. I wanted it to replicate my work rifle, which has a Surefire 900 series, so I grabbed it based on the ergs (fits my hand really well). I've used it a little, and it seems to be holding solid. Kind of hard to screw up the design. The slot for the pressure pad let me slide the pad I have under the edges, then secure it with the screw, no glueing.

I do suspect that if you kept putting it on and taking it off, it would start to wear down and loosen up.

I leave mine empty, I hate stowage on rifles.

Hate to revive an older thread, but in case anyone is wanting one of these UTG grips, Cheaper Than Dirt has them sale priced in the latest catalog for about $12.

www.cheaperthandirt.com/ARR073-41693-1888.html Black
www.cheaperthandirt.com/ARR075-41694-1888.html OD
www.cheaperthandirt.com/ARR087-41695-1888.html Tan