Literally speaking, whenever someone violates your unalienable rights*, with open violence, you have a right to defend your self by any means necessary, to preserve your life and limb from serious or lethal injury. This includes the use of a firearm of any type, size, or power.
What ‘authority’ the violator claims is of no objective consequence so far as your rights are concerned — and declarationally speaking, of no legal consequence.
Good video, good article, give it a watch/read.
— Anthony Dream Johnson
*If you forfeit your rights by violating the rights of others, this no longer applies, such as when a criminal robs and murders someone, and is then shot by police in pursuit, an armed citizen seeing the conclusion of the crime and attempting to stop the criminal, etc.