[Kameron8]

Gunfighter Boots do not function when used in conjunction with the bare fist gun replacements of Mechanations or Karakuri.

To replicate:

1.  Make a Karakuri, get their hidden barrage trait.
2.  Equip Gunfighter Boots.
3.  Kick, and note that your guns are not fired.

[Neus]

Not a bug, Gunfighter Boots will only trigger if you have a Gun weapon equipped.