The OKC S3 Marine Fighting Bayonet grip is about 1/16" longer than the M-9. So is the Army's Tanto bladed version. They will fit rifles. They may NOT fit shotguns quite as well -- you are warned.
The M-9 is, in fact, cheap 420 stainless steel and won't hold an edge. It is meant more as a corrosion-resistant sharp pry bar only without a full tang. If you want decent steel, as in a knife, just like it get the 1095 carbon steel bladed M-10 -- it'll be at least moderately useful as a knife but you'll have to maintain it a bit more.
Last edited by Gehrhard; September 20, 2011 at 06:46 PM.