When I press Z with a gun in my hand, nothing happens. I verified that this happens with nothing but this mod installed, so this isn't a shortcut conflict or incompatibility. The log contains no messages that I would consider suspicious.
Forge version: 41.1.0.
Mod version: 1.2.8

Oh, I've just noticed that the name of the latest commit in the repository implies that it fixes this. Nevermind, then