Bottom pic: Fin stabilized HEAT round 125mm. Eastern Bloc stuff probably for the T-72 tank. Looking at the standoff spike I'm assuming it's been rendered inert. Hope so anyway :-)
Hit it with a hammer and let us know what happens.
Just kidding, pizoelectric crystal in the nose requires "setback" i.e. recoil to arm the circuit.
Where did these things come from? Gun show souveneirs or something?