If I recall correctly the years are right, 1948/9. Same as 740? but with an aluminum frame. Pretty receivers with molded, I think, scroll work. They have a friction ring for adjusting to 'high brass' and 'low brass' loads; .
Slight correction: Friction piece stays in place and is not adjustable.. But the compression ring is movable and is placed differently for low power loads vs. high brass stuff..
