I recently bought 250 FMJ 9mm 147 grain bullets. Weighed my lead balls and replaced them. It took 130 to slightly increase over the weight of the .50 cal. balls in one jar. If it works well, I will buy more for the other jar, or make up the loss with the lead balls. They were non magnetic and cheap enough, that I didn't have to make the copper pipe filled with lead, which I was going to do. I'll find out shortly how they actually work. Hopefully, it was not a mistake. They LOOK like they will work very well.