[b.goforth]

j,
without knowing the exact marking on your revolver i am going to assume a few things. first would be first that the first digit in the serial number is an I and not a one (iver johnson serial number were only 5 digits with a letter prefix), the I letter code on a second model (owl head looking at barrel) would be manufactured in 1903. this is a black powder only model. for one safe with modern ammo your need a third model (1909-1941). look for one that has a coil hammer spring. first and second models have a single flat leaf hammer spring.
bill