Sorry for the late reply, I was quite busy lately...
Anyway, you're only legally allowed to discharge a FIREARM on a gun range, or if you're a hunter in a hunting zone or area. On the other hand, if you've got an over-18 weapon of any kind ( airgun, bow/crossbow... etc. ), you can shoot it pretty much anywhere outside of the bounds of residential areas, such as cities, villages or otherwise outside of registered settlements, as long as nobody is at risk of being injured, or any property damaged.
This is the official stance of the law here in Slovenia on the use of over-18 or registered weapons.
Now, read between the lines - the law states that you're technically allowed to shoot your airgun ( whether it'd be registered or of an over-18 type ) anywhere outside of the residential bounds (250m out is the unofficial declaration), or if the landowner of a certain area explicitly allowed you to shoot your airgun on his/her land; Which means that on a public piece of land where there's no private owner and which is located out of settlement bounds, you can shoot your gun without an issue of legal nature
An example would be an isolated patch of forest (there are plenty of those), where no one can see you and even if the police come by, theoretically speaking (for instance, they could be looking for illegals crossing the border), they'd have no legal ground to arrest you, or tell you to go elsewhere!
One more
VERY important thing, always conceal your weapons when carrying or otherwise transporting them (either personally or in a car), use a duffle/rifle bag, a case, anything, as long as it conceals your gun.
Another thing you should know about are the categories of over-the counter, or 18+ types of weapons; These are the types of weapons for which you don't require a possession permit, an arms permit, or registration, only your ID card that states you're above 18 years of age.
- Airguns up to 25J,
- Crossbows/Bows - not limited to power output or velocity,
- Slingshots- not limited to power output or velocity,
- Airsoft guns,
- Blank guns ( front or top firing ) - Front firing guns must be compliant with 2019/69 EU directive. ONLY flare adapters are legal!
No rubber ball adapters are allowed to be in possession (SAPL, Self-gomm, POM 15mm, aftermarket calibrated barrel adapters... etc. )
- Antique guns (older than the year of 1865) - Must be genuine antiques, not reproductions. Reproductions require registration!
Which part of the country have you moved to? Hope you haven't moved to Ljubljana... To many people roaming the forests around it.
That's pretty much all there's to it, I hope I didn't bore you to death with all of this info, but you should be able to adapt just fine.
Have a good one and merry Christmas/ new year!