Ok, Here are the dimensions on my 1930 Type A 9.3x62mm 1 serial number off the Osa Johnson rifle.
Diameter under the sight base is .990" the step dia. is .900" step length is .220", barrel dia. directly in front of the step is .801", measurement from front of receiver ring to front of sight base ring(beginning of step, breach side) is 5.680" measurement from barrel muzzle to muzzle side of step is 17.062"