I need to buy a couple lower parts kits to finish some projects, and other bits and pieces.  Sometimes my packages get opened by the little ones before I get home, and if it doesn't say 'gun' or 'firearm' in the companies title, the Mrs is happy because she thinks it's tractor or car parts or whatever...  She has been super understanding of the AR's I have, I just want to build up my inventory of spare parts and whatnot...  Ok, I have out of control BRD.

Best company that doesn't say 'Bobs Guns' on the box?  Larue Tactical goes under the radar just fine.

Communicate moar.

Maybe there's a reason you're too embarassed to tell your wife what you're buying.  Maybe you should either: (1) explain to her what you're buying and justify the purchase; or (2) re-evaluate whether you're embarassed because you know you actually shouldn't be buying more stuff.