To be able to shoot it with blank loads for re-enacting, your only lawful option is '3'. An original black powder firearm possessed without license as an 'antique' may not be fired (blank or otherwise). An original BP pistol that you wished to use with blank loads for re-enacting would have to be on a 'C' license. It is stupid to use a valuable original when a stronger replica is much cheaper. You don't actually need a theatrical endorsement if the event is under the control of someone who is appropriately licensed. Your C endorsement would allow you to own it and carry it to such events (appropriately secured in a lockable container).
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