I have ToolCraft and BCM bolt carrier groups, T.C. is nitride, the BCM is perfectly .mil spec in every way. They both work flawlessly, the T.C. bolt is a little slicker and much more affordable though, and since nitride is a treatment that effects the surface of the metal, it wont chip, like a plating and wont wear like most coatings. ToolCraft doesn't do high pressure testing on their bolts to the best of my knowladge, but they have made BCG's for the U.S. military though so they know what they're doing. By making a bolt correctly but not H.P. testing it's actually stronger as the testing somewhat fatigues the metal. I wouldn't be to worried about it though, if you shoot enough ammo to break a properly made BCG, you have actually accomplished something.
That truly has to be the highest quality per dollar ratio of them all. No it's not .mil spec but as some have become aware, that's a standard, non-mil spec can be worse OR BETTER!