Legality

Legality in the US:

2mm pinfire miniatures are not considered weapons or firearms by The United States ATF (Bureau of Alcohol, Tobacco, Firearms and Explosives)
You can visit this link for more information: https://www.atf.gov/file/58196/download

And more specifically read Section 2.2 Antique Firearms, where it states that "any firearm using a matchlock, flintlock, percussion cap or similar type ignition system, irrespective of the actual date of manufacture of the firearm, is also an antique firearm"

Section 2.2 Antique firearm. Firearms defined by the NFA as “antique firearms” are not subject to any controls under the NFA.22. The NFA defines antique firearms based on their date of manufacture and the type of ignition system used to fire a projectile. Any firearm manufactured in or before 1898 that is not designed or redesigned for using rimfire or conventional center fire ignition with fixed ammunition is an antique firearm. Additionally, any firearm using a matchlock, flintlock, percussion cap or similar type ignition system, irrespective of the actual date of manufacture of the firearm, is also an antique firearm.

Legality in Europe: