Well, the casings can be had and I'd take it as a personal challenge to create projectiles...BP filler I should think. I can rejuvenate the primer tube with flash or 4F and use a shotgun primer to fire it... Exactly the reasons I didn't buy a 60mm mortar that was at auction.
But yes, unless you pull the dog's teeth, you can't beat him without getting bitten...then you can do what you want.