You can load as light as you want, but you should stay above 600 fps or you might stick a bullet in the barrel. You can look up loads for the .44 special, .44 American, or the .44 Russian and see how they perform. You will get less velocity since you are using a longer case. Trail Boss can be your friend. Look up some cowboy loads for the .44 special. Them cowboys are shooting the weakest loads they can get.