Got the chance to go out today and the results are in! The plumb bob is somewhat difficult to aim but I've been using heavy stones and a heavy ball bearing so I'm not so used to light ammo. When I did get it on target, it was pretty darn effective. The tip of it isn't that hard and rolled a bit with just the first direct hit but honestly it doesn't make that much of a difference. Its a pointy bit of metal and it hits hard whether it's sharp or not. It didn't quite punch all the way through but it got darn close. I wasn't throwing full power but I think it would have to have that very sharp point, maybe with a square cross section, to get all the way through. I did get one glancing shot which roughed up the side of it quite badly which shows the metal isn't all that hard. Really I don't mind because it was cheap and I didn't expect much from it so all in all it makes great ammo. I'm not entirely sure, but I think I managed to give it some spin on the release. The wool was almost always twisted as if it had been spinning whenever I went to collect it. Yet again I find myself wanting a slow-mo camera...
I also managed to find some suitable trees to hang the pan from which didn't make it much louder than when it's on the ground so I think I'll be doing that again in the future. I didn't get any photos of it up because I got a bit distracted by a slight problem I had...
I lost the 2 inch ball bearing. It's currently somewhere in a bush. I have no idea how it was lost really as it's large and really shiny. It should have been easy to find! It got too dark to keep searching for it so I'm going to have to go back tomorrow