Recently had the money build a descent AR, but I saw a Sig that I just had to get. This is my question and I am looking for sound advice. I want to build a 556 SBR suppressed and 6.8 SPC with a 20" barrel. First question, which should I build first? Next question, which receiver set should I get? My original plan was a billet from mega or spike, but I have 6 month daughter and gotta a bit smaller budget now. I'm thinking a good forged 7075 set. I also want to know what barrel manufacturers are good quality and not price rapist I have a rockriver entry tactical CAR A4 and S&W M&P 15X, my S&W is going to get a 20" fluted heavy and RRA has a Daniel defense rail and both are good as is. This pistol is why I scrapped my previous build plans. I need good advice cause rifles are new to me.