[Trailerpark Badass]

You are right. It was also gas-operated as was that other great WWII infantry weapon the BAR.

The Browning .30 cals are recoil operated. They need one of these:

screwed onto the muzzle, as well as a cartridge stop installed in the feed mechanism.

It is highly improbable that a soldier trained enough to get and keep the weapon firing would not know he is firing live ammo.

[Trailerpark Badass]

Should say they need that adapter to fire balnks.