Armor piercing weapons?

[Merr]

Hey, so I found a secret layer in the bank, but there is a mech downstairs which i cant seem to kill, are there any armor piercing weapons that i can find and use to get further in this secret layer?

[fix your posture]

p90

[Generic Catgirl]

orgone sniper, or just lug a mechscale weapon down there.

[spooky]

try entering through the roof of the elevator, it'll lead you through the back where you'll find a gun that can deal with it

[TENGU48]

you can technically bring a mech weapon with you on-foot. Those are easily capable of killing the mechs but will weigh you down severely.