I have put several coats of Alumahyde II on a Ace shorty stock over the past couple weeks.
Is is best to finish this off with a clearcoat of some kind or let it be?  Do they even make a matte
clearcoat, I dont want it to be shiny.  Thanks.

I don't think it's necessary. That stuff gets tougher the longer it's on, IMO.
YMMV

And I can tell you this from recent personal experience.  What Brownell's calls matte clear coat Aluma Hyde is NOT matte finish.  At best it's a semi gloss, and it looks crappy on anything you put it over.

If you want to put a little extra water resistance on your piece, go to Wal Mart and get a three dollar can of Krylon CrystalClear Acrylic, part #1313 clear satin. Sprays on easily, dries to the touch in 15 minutes, and won't hurt a durn thing. Water on it just forms droplets you can shake off.

Quoted: And I can tell you this from recent personal experience.  What Brownell's calls matte clear coat Aluma Hyde is NOT matte finish.  At best it's a semi gloss, and it looks crappy on anything you put it over. If you want to put a little extra water resistance on your piece, go to Wal Mart and get a three dollar can of Krylon CrystalClear Acrylic, part #1313 clear satin. Sprays on easily, dries to the touch in 15 minutes, and won't hurt a durn thing. Water on it just forms droplets you can shake off.

+1 on the so called matte clear coat Aluma Hyde II not being matte and looking bad.  

I used some Alumahyde II  tonight.  I don't think it needs anything further for protection, but a layer of clear would look better.  I am going to try the Krylon CrystalClear sounds promising.