If you have a Winchester levergun, it is rated at 45,000 psi. The .357 Magnum was originally a 45,000 psi rated load. Commercial .357 Magnum loads are well under 40,000 psi levels. Most all commercial ammunition under performs anyway. You can safely build a +P .357 load for a Winchester.
I agree, even though I have never seen the forest fuzz get off their behinds and check someone firearm in the field, it is best to obey the laws of the state for the sake of fair play and staying legal. In this case if the law were to say no .357 Magnum's, then you cannot use one. That's it, no exceptions. But, if the law states a minimum requirement in energy levels and a cartridge is capable of doing so, then use it.
Besides, when did this thing get legal anyway? The original post stated nothing as to whether is was legal or not, but rather if it can be done or not.
[This message has been edited by Robert the41MagFan (edited February 13, 2000).]