Uhmmm, yup, reenacting is quite popular over in Europe. They even do American Civil War in addition to Napoleanic stuff and even Viking and mideaval combat. And yes, it's a blank and that's how they look depending on how much powder used. When I was doing Civil War, we were told to use only 60gr for our blanks, but rednecks and good ole southern boys, we used 90+. The 60gr charges made a "whooof" sound while 90gr had a proper bang.
These days I'm shooting live ammo in North South Skirmish Association competition and it's pretty cool when you can hear a gun go off and almost immediately hear the "whack" of the ball hitting the target downrange. The effect is especially noticable in smoothbore matches. Couple that with the vapor trail left in the air by the bullet on humid days and it's all very cool to watch bullets all the way to the target and hear the whack of impact.