Good info search Ocin. Never thought to Wiki it. Still, according to the piece, even the M3s in 9mm went to the Brits, so export is the logical answer. Never new there were any made in 9mm. There must be lots of this ammo around, especially in GB, as no purchase offers have come in.
I fired an M3 years ago and agree with most who had the experience. Butt ugly but very small and reliable. I was pretty scrawny then and the gun push-pulled me back and forth, following the movement of the heavy bolt as it fired.
Thanks, Mac.