Both are power house calibers, well maybe at today's standards just magnum loads, in any event both are fairly uncommon although they are both available in T/C barrels and Wildey still makes the .44 Auto mag I don't know of any current semi's in 451DM. Depending on the headstamp the brass may be worth a bit. The .44AM is current from starline no curretn 451DM is available.
