Sounds like you're looking for a weapon to abuse just because you have this "free" ammo. It isn't free if you have to buy a particular firearm in which to shoot it and then commence to beat up that firearm.
Analogous to this would be if your Grandfather had given you a bunch of old/drain oil or gas and you needed to go out and buy a crummy old pickup truck that doesn't care about fuel/lubricant quality.
Pull the components apart, save what you can identify and drive on.
I just finally started shooting (and stopped) a pile of .38 wadcutter that came my way on the cheap. It was so gawd-awful that I figured free was too expensive and salted it away again till I feel like dealing with it.