[45Auto]

From the images, it is a 3rd Model, Safety Automatic Hammerless revolver. It was made for modern ammo. The 1st and 2nd models were made for cartridges loaded with black powder and for this reason, it is unwise to shoot them unless you load your own black powder .32 S&W ammo. The 3rd Model was improved in many ways including strengthening it for modern .32 S&W ammo. Thus, if your little IJ is otherwise is good mechanical condition you can use modern factory ammo to fire it.