That was probably my crew, the Camp Blanding Historical WW2 Museum. I usually work that event, manning the tables and doing the blank firing demo (when the park allows them to have it)...I had other plans this last weekend, though, and missed out. I've been a volunteer with them going on 12 years now, living only about 7 miles from the museum; we also do a big Memorial Day shindig there at Clinch every year, too.
I can vouch that most of the display weapons we have will live fire (excepting that 1911 and the revolvers), having carried the Thompson and the BAR in many living history battles, much to the chagrin of my aching back and feet, lol. As a matter of fact, that FA M1A1 Thompson is what give me the desire to own my own, albeit semi-auto, version.
Rob