Frame marked "HERO" and "M.F.A." (Manhattan Fire Arms),
serial numbers, when found, are stamped on frame under the
grips. Estimated Production 5,000+.
Guesstimated Serial range #1 to 5,000+.
I have been able to check out this pistol first hand.....really neat !! I have been to these copper mines with Whispers and there is still MANY areas here to MD. LOTS of stuff still to be found. Cool pistol !