I have several old Iver Johnson revolvers all of them are the ones with the owl looking forward and supposedly BP frames. I have shot quite a few light loaded smokeless loads in them over the years and have not blown one up yet. If you choose to do this do what I do, that is I look at the loading data for the cartridge and start and end with the lightest load listed. I mostly shoot a 38 S&W one and usually shoot 125 gr cast bullets with a light load of Red Dot. I have Chronoed my load at 550 fps. Not a power house load but it is fun to shoot.