There isn't much purpose to a heat shield, they are mostly for looks. The old trench guns had them so you could grab the entire gun when you were sticking a German with the bayonet.
The ATI stuff seems to fit alright. We have a bunch of their stocks at work.
Thanks for the info. I figured they were mainly for looks. Still undecided if I want to use one or not. Prob gonna get one from Moss directly. I don't think that I will be sticking anyone with my bayonet.
You don't need one for home defense, hopefully you wont need to shoot enough rounds to get the barrel that hot. If you got some land to shoot on and plan on shooting a 100+ rounds, you'll be glad you got one. If your barrel is 20+ inches, make sure you get one with the spacer or it will jump around and scratch your barrel.