what would the energy (ft-lbs) be for remington umc 125 grain JSP 357 magnum out of a 16" barrel on the website it says 583 ft-ibs out of a 4" barrel handgun. also what would the velocity be out of a 16"barrel?

thanks,
mitchell

You'd have to shoot them to be sure, but figure somewhere between 300 and 500 fps additional velocity, probably toward the high end of that range.