AR-15 vertical grip

[earl_simmons]

I've been using a DSA vertical foregrip that is secured in the typical manner (screw-in protruding nipple). I've noticed that the base of the grip tends to unscrew during each shooting session. Is there a similar cylindrical grip (not a unidirectional grip like the Fobus) available with a more secure method for rail attachment? Something like a spring-loaded tab, perhaps?

 

[gun-fucious]

have you tried the real deal Knights?
http://www.impactguns.com/store/kmc_pistol_grip.html

53 bucks