[Fido969]

How about my black powder .58 cal minie balls?

[Gen.Blather]

Here’s your answer.

https://www.atf.gov/explosives/qa/black-powder-subject-regulation-under-federal-explosives-laws#:~:text=However,%20the%20law%20exempts%20from%20regulation%20commercially%20manufactured,%22destructive%20device%22%20in%2018%20U.S.C.%20921%20(a)%20(4).

[Scrambler Bob]

How about my black powder .58 cal minie balls?
= = =

Convert that to some metric version.

Like .00001 kilometers.

You should be fine.