I have sharpened mine to 15 degrees and it has done two deer, gut, skin, disassemble and some of the boning out. The nose is actually a little steeper, probably 10 degrees. It remains shaving sharp and likely will not be used until next year.
I have very often sharpened knives of decent steel like this, and the only ones that I will not do this steep are the carbon steel blades that are much more prone to corrosion. Those knives, like the old Sabatier carbon blades will go dull just from cutting meat and washing them. I strongly suspect that it i because the very, very fine edge has a tendency to corrode rather than wear. IMO it would be a complete waste of time to put them on a water stone and polish the edge at 5-8 thousand grit. M4 it seems to me is well more than corrosion resistant enough to warrant it though. The patina on the blade has not changed since last fall.
