I just put together a rifle with a Del-ton heavy mid upper non chrome lined. I don't like that the firing pin retaining pin sticks out from the carrier on Del-tons Other than that just from looking I can't fault the unit. The aluminum heat shields could be blackened. minor stuff.
Here's the fun part: this rifle (including lower) has parts from Del-Ton, LRB arms, Stag, DSA, Palmetto, UTG; Frankengun!