How do you use the Skull Gun?

[frank ugly]

Pressing 3 doesn't seem to work and just uses whatever I have equipped on the arm

[jesusgirl69]

Cant Figure Out This Either; Would Love Cllarification

[Marneus]

The skull gun will only fire if you drop a gun and then press fire from your empty hand selected.
I haven't found it to be really useful honestly.

[[w] BerlinerMomCargoBike]

i like it b/c you can use it to break doors n stuff so u can have something else in grenade slot

[Modern Horror Gaming]

exactly its so you can blow up doors and secrets without having to use your arm slot for nades or your weapon slot for rockets, so you can sub for your head slot, which isnt that bad compared to cheap options