Quote from gwb-trading:
These guys shot with both .22s and M1 Garands; they had to make changes to the outdoor firing range back in the WW2 days to support the M1s. The indoor range only supported .22s.
Maybe they only got the firing pins for assembly when they showed up to the range. I never really watched to see. I saw that they passed out and kept track of ammo & had plenty of instructors keeping an eye on everything. All competitions I believe were done with .22s, but the M1s were used for qualification/training.
The demostration rifles (parades) that they carried around at some show-off events were fakes.
Sadly in the modern era, they do not have the outdoor range anymore, but still have the indoor range with 22s.