I am in the market to purchase a backup gun to carry around my ankle. I have narrowed it down to S+W, the 442 only comes in 38special while the 340pd comes in 357mag. The difference in price is 200.00, the 340pd being the more expensive. Is it worth the cost to get the 357mag? I carry a Dept. issued SigP226 40cal on duty this will only be used as a backup or off duty once in a while.