My dad saw quite a few injuries from people using powerbelt bullets. I have seen a few myself. I'll agree they are in the top 5 of accurate bullets on the market for muzzleloaders, but in terms of terminal performance, they are well in to the bottom of the list. In my opinion anyway. I've just seen a few for myself but have heard many horror stories about shoulders blown apart with little to no penetration. One of the one's I saw for myself, the guy hit a very nice buck at just a little over 50 yards. Buck was quartered away a little bit. He hit it right dead in the pocket. We lost blood at around 40 yards. After 2 hours I jumped the the buck and put a 275gr maxi through it's neck. On field dress, we noted his absolutely perfect shot looked like a grenade had went off under the shoulder but not a single hole in the cartilage of the ribs. Sorry but just accuracy in a bullet does not a hunting bullet make.

All of the things brought up are true, my personal experience was having one blow on the shoulder of a nice buck and having to get tracking dogs to find him then shoot him again.
There is another answer if you are stuck with a bunch of them, just fill the HP. with solder.

injuries to the user?

Used them all at some point in time. I'd use them again if I ever get bored with cheap home cast round balls.

Honestly MountainDevil54, I have had better experience with round ball than what I've seen from Powerbelts. Not in the accuracy department of course as I will always concede the powerbelts are very accurate out of most barrels. That is amazing in itself to be honest. Not many bullets out there for muzzleloaders can claim good to better than good accuracy out of just about every barrel. Not honestly claim it anyway. If they would just make the things penetrate better and not be so fragile they would be worth the premium price being asked for them.

Been reading and watching more but with this I have to beg to differ.
I've shot a truck load of different bullets and there are many that completely out perform those bullets, both in accuracy and performance.
I'll refrain from my complete negative thoughts with the bullets, but I will say they melt down and make great fishing sinkers.

It's simple. Don't push the PB too hard and don't shoot shoulders. Some can't get it through their thick head that more is not better. Keep the velocity down and they penetrate fine.

Hell, I wouldn't shoot a shoulder if I was using the toughest bullet made.

Glad you refrained from using negative thoughts.

Well...... there could have been a ton more, but I refrained

You must be upset that they killed more game than your bullet?