A while back, there was a really good (and long) thread on AR-15s on a certain tactical forum. A mention of loose barrel nuts somehow made it’s way into the conversation, and one poster mentioned that use of a forward vertical grip (with non-floated handguards) could possibly contribute to a loose barrel nut.

Would this be possible, and how likely would it be to happen? How heavy would use of the forward vert grip have to be to loosen a barrel nut? Has this ever been a concern to any of you who use a vertical grip?

Never. I don't see how on a none float tube the use of a vertical grip could cause a barrel nut to loosen. Barrel nuts loosen for only one reason. They weren't torqued down propely when they were installed.

IPSC_GUY sends

the only experience i have is with gi, RAS II, and a FF quad rail tube.  

GI the most you could do is f up the HG. the aft end would move within the delta ring w/o transmitting torque to the barrel nut, the gas tube would start to impinge on the hg as you rotated the HG.

The RAS II upper is prevented from rotation by the bridge, the lower is retained by the upper.

The quad rail would come unscrewed from the barrel nut before the nut would loosen.