I think, particularly in the current climate, it is necessary to have a ‘No OOC threat’ general rule.
By this, I mean that, if playing in a public area, nobody in character should appear (after initial glance) to be a threat to mundanes.
This is more important in ‘modern time’ LARPs such as Vampire-Masquerade where it is possible for players to be carrying physical reps of weapons and firearms. The last thing you want is for a mundane to get the idea that theres a real ramed gang war/robbery/murder going on and call in the SWAT team! To prevent this, any firearms would be represented by the brightest-coloured water pistol money could buy. I know this is not exactly realistic, but in this case, you don’t want realism unless you are not in a public place. Alternatively, we had some replica flintlocks which are sufficiently different from a ‘real’ gun - provided you are in costume, in daylight.
Of course, in Mordavia, being dressed as a demon or carrying a foam sword is usually a dead giveaway that it is some form of acting!
Currently, there is no way I’d want to be LARPing a character with a firearm in a public place in a UK game …
Steve