Frontier brass is part of Hornady's line, and I think Remington draws the brass for them. I find it a bit thicker and therefore heavier than WW brass, but completely serviceable and accurate; you just have to back off the powder charge a bit.
I'm not sure how Hornady specifically uses the Frontier name-- as I've seen two boxes of rifle ammo, both new, both made by Hornady, with one box full of "Hornady" and the other box full of "Frontier."