Your other thread asking this same question
Same answer still applies from me.
Pourable epoxies have an advantage over thicker brands for forend stabilization, but they're awful for action bedding, because you can't really get them to stay in place where you need them. It's not prohibitively hard to use thicker brands for forend stiffening though, so generally, I just use the same compound that I used for the action bedding.
As I mentioned in your other thread, I don't like the method of simply filling the forend with epoxy without embedding some kind of "backbone". I route a groove down the center and embed a steel rod or flat-bar, or aluminum V-channel, then bury that in epoxy. Much more stiffness with less total epoxy volume.
I'm sure that the Matchgrade product is just as good as any other pourable epoxy
for forend stiffening. There are better products for action bedding - not pourable, and more durable.
Whatever product you use, be sure to rough up the interior of the stock sufficiently to give a good "bite" between the epoxy and stock and degrease the interior sufficiently to ensure good adhesion, otherwise a few years from now you'll be able to pull the barreled action and your epoxy will fall out of the stock like ice cubes from a tray.