I'm not sure...
You can find it out with this way:
You need an account which don't have the "GUN HOBBYIST" (you have to got 15 permanent weapons) or the GUN COLLECTOR (you have to got 25 permanent weapons) ribbon.
Now,
You have to get 14 of 15 permanent or 24 of 25 permanent weapons.
You'll buy the Combat Axe now.
On the next day you'll see if it counts...
On the same way you can find out if grenades, the m16 or/and the m700 counts as a permanent weapon.