For Slovakia, you could consider the Bratislava Rifle Range:
Bratislava's premiere outdoor rifle shooting range is the setting for our most popular stag do activity. You can have a blast shooting a real Scorpion machine gun, sub-machine guns or a selection of handguns supervised by certified instructors. We guarantee you will love letting a fully loaded machine gun go off at the rock above the metal targets with unbeatable sound and smoke effects.
In Poland (Krakow), there's the Gun Shooting in Krakow option:
Our firing range offers you the chance to fire some of the world’s
best know guns such as the infamous Kalashnikov, the AK47, a revolver,
various pistols such as the Russian MCM Margolin and the Austrian
Glock as well as a traditional shotgun.
and in Hungary, shooting near Budapest:
Heavy-duty guns and real firepower (like Kalashnikov AK47 and many
more), you can experience the power in your hands, which is
In Slovenia, Shooting in Slovenia (some NSFW pics) offers the following description:
Shooting in Ljubljana for stag parties, is one of our best sellers. If
you’re asking yourself, why? Then you obviously haven’t gripped a
hardcore firing weapon, and blasted off a target board. The power of
the gun sends a rush to the arms with a rigor of excitement….just
holding this deadly gun, you have become a lethal weapon.
But stuffed if I can find anything in Croatia...