Did Abner actually fire the first shot from Fort Sumter?

No, You know he didn't.

But as you know from re-enacting The man who pulls the lanyard on the cannon wouldn't do any damage if someone else hadn't already loaded the powder and the shot. So who is more responcible for the damage done by the cannon shot? The man who pulls the lanyard? Or the man who loads the shot?

In actuality they both play their parts to make the whole thing work.