Deactivate it and its not considered as a firearm anymore, you have to show it to police in 30days after import tho. That is if i understood law correctly, better ask from embassy.
Firearms act
Section 112a
Transferring and importing to Finland a firearm rendered permanently unfit for use and a
permanently deactivated firearm component (601/2001)
Anyone who transfers or imports to Finland a firearm rendered permanently unfit for use or a
permanently deactivated firearm component shall, within 30 days of the transfer or import,
present the firearm or firearm component to the police department for examination.
Off topic but i found something amusing
I wonder what kind of work could need rocket-launcherA permit for an automatic firearm, grenade launcher, mortar, breech-loading cannon or for a
firearm of a corresponding structure and purpose of use, for a missile or rocket-launcher
system or for a component of these weapons may be granted only if the purpose of use notified
by the applicant is a show, filming or a corresponding presentation or keeping in a museum or
collection. A permit for the above mentioned firearms or their components may, for a special
reason, also be granted for work where a weapon is necessary.
