Singer made a small number of M1911 .45ACP pistols during WWII.
IIRC, they’re some of the most sought after and valuable M1911s ever made.
You are correct. I believe Singer sold their contract to Remington Rand before a thousand were made (possibly as few as 500). They are sought after, and also very frequently counterfeited. Swindling 1911-A1 collectors has become a booming business over the last few years.