I was looking for a new knife recently after temporarily losing one of my favorite fixed blades, since the AW ban had just sunset I figured why not get a bayonet and "evil up" my rifles that now have bayonet lugs.
I wound up getting the M9 and it's a pretty beefy son of a bitch, I kinda like it. Fairly expensive but now I've got yet one more fixed blade to abuse after my friend found the SOG Gov't. Recon that I had lost while he was going through his camping gear.
The thing fits great on my 14.5 inch gun with Phantom but it is a hard fit on my 20 inch Gov't. with Phantom. For some reason it seems the bayonet lug on my 20 inch rifle is slightly off in alignment, clicking the M9 into full engagement takes some doing and then to get it off it's pretty difficult as well. I suspect this would happen with most any bayonet I tried due to some kind of alignment issue with the lug itself.
Here's my rifle with M9,