Over the years I have shot my fair share of watermelons and other fun targets. Normal bullets do a ton of damage, especially the ones I fired from a high powered rifle. One time, I completely obliterated one using a shotgun loaded with a 3.5 inch Turkey load, but never in my career of watermelon shooting have I seen the damage done by these 9mm bullets loaded with reactive liquid metal.
The Backyard Scientist made some bullets loaded with sodium, potassium, and a special alloy of sodium & potassium (which happens to be a liquid at room temperature). I have no idea how they made it stay in bullet form when it is a liquid, but somehow they got it done and the results speak for themselves.
The cool thing about these metals is that they are super reactive to water, meaning there is a violent chemical reaction when the two come in contact with each other. Now add the chemical reaction with the already destructive power of a bullet and you get some destruction. Do not just take my word for it watch the video.
The video goes into some science stuff that is a little over my head, but I fine with that I just like watching fruit explode.
Unfortunately these bullets are not for sale and it looks like you would need a background in chemistry to make your own, so most of us won’t be shooting these anytime soon.