I assume you are talking about Essential Arms J-15 Lowers.
They are the best cast receivers on the market. Most, and the current ones, are investment cast by the casting division of Ruger, and finished by Essential. They come in the old gray color anodizing, about the color of a USGI magazine, like the old original M16's. There are currently no matching receivers made.
I have seen a lot of these lowers and have NEVER seen a malfunction that was caused by the lower. They are well made, and fit most uppers well. You could spray it with Norrells, Durakote, etc.
I had a rifle on one of these lowers years ago, and would not hesitate to buy another one.
Hey, you could match it up with one of the "blemished" uppers from LAR-Grizzly, spray both at the same time with whatever color you want.
their ad says forged or cast same price. anybody seen their new forged receivers? if i remember right the ad also mentioned a stainless steel version was available.