I am putting my second AR together and looking to do an 18 inch SPR type. I'm not trying to break the bank with this upper as I'm not doing competitions. I have seen a few DPMS barreled uppers on the PK Firearms website that fit the bill but I don't have any experience with the brand. The upper I will jump on if the money allows is the Stag arms 3G upper, it's set up just the way I want just wish the stainless barrel was black stainless but I could get over that.