Last thing I heard was the Fulton's carriers are simply stock DPMS pieces, and if so, you might want to look for an early Colt. They are out there.
Two reasons for this. 1) Internet rumor has it that DPMS isn't making the thing any more, though you could call and check that. 2)The DPMS chrome carrier I once owned for a couple of weeks was the crappiest looking thing I ever saw. Full of tool marks and gouges. Others have posted similar comments.
Not trying to put you off anything, but it wasn't hard for me to find an original Colt smoothside bolt/carrier assy awhile back, and I periodically see them in the EE section of this site. Prices are usually a bit higher than I paid two years ago, b/c of all the interest in the early stuff these days, but it wouldn't cost a whole lot more than the repro.