i admit that i'm picky about my nylon sheaths.with that said i have never like any of the nylon sheaths like the ones busse,scrapyard,ranger or RAT cutlery offer.
they will do the job but for me the only nylon sheath i will pay for is SPEC-OPS brand.the scrapyard site says their sheath is cordura but they dont look or feel like it to me.maybe they are a lesser denier because 1000 denier cordura looks and feels much thicker.
i rally couldnt tell you if one will fit a FFBM.
dont get me wrong though,they will do the job.i'm just a knife and knife gear snob.thats why i but busse.