Not sure about yrs they made fat vs skinny forearms. This one is from the 70's. Some of the older ones are fat, and I think they're ugly. I would guess '50's or so for fat ones. Maybe someone can chime in with more precise info.
The tang sight is pretty neat and doesn't interfere with the bolt. One needs to hold the thumb along side the tang and not try to wrap it around the grip, as it won't work that way.
DF
