I guess I should also say that ALL my other bolt carriers are M16 style and have a chrome lined bolt portal and chrome lined carrier key port.
I agree that DPMS chrome bolts and carriers aren't the best by far, they hog out too much material on the carrier like a Colt for one.
Smith uses D marked carriers which as far as I know, DPMS is the only manufacturer that marks their carriers with a D but Smith also uses M16 carriers, does the milling on the AR15 carriers and also does the chrome plating, DPMS doesn't do the chroming for them.
Smith Bolts are also the only chrome coated bolts I know of that are magnaflux particle inspected, each and every one.