bj139 Wrote:Does the Flex Seal stick well to the plastic, carbon fiber handguard?
Yes, if properly prepared.
Carbon fiber needs to be very clean and roughed a bit. I very lightly hit it with white aluminum oxide through my ultra-cheap Harbor Freight blaster. Ultralight sandpaper would probably work as well. Clean afterward very well with high grade alcohol. Finger oils can screw it up, as can leaving a bare spot or edge, or touching it before it's cured for 24hrs.
In the previous photo, you can see where I tripled the coating on the front edge. The rougher under-coat is actually Rustoleum's rubber coating Leak Seal. It doesn't apply as smoothly as Flex Seal. While you can't see it in the photo, the grip on that carbine has Flex Seal applied to its bottom half.
Of course, YMMV. I'd experiment on other things first to get a feel for it. I wouldn't do it to a Clark or AP Customs unit until they were well-scratched from use.
I've done handgrips and solid aluminum hand guards and metal Barrett 6.8 SPC metal magazines when they started to show wear. Flex Seal has hokey commercials, but it's a pretty good gun-hack product.