The old and long winded in this field are the brother's Corbin. Dave at swage.com, corbins.com, swagedies.com, etc. and his brother Richard at rceco.com. BOTH have books for your complete edification on their web sites. Download, etc. (Without pictures regrettably but you don't miss much.) As indicated, the lead is formed with or without a jacket by high, really high, pressure. Most forget that RCBS stood for Rock Chucker's Bullet Swages. And the press was for turning .22 fired cases into jackets. Names like Hornady and Speer began this way. Fascinating field and much to learn if it interests you. Most basic. Major makers have a tolerance of 2 or3% or more % weight. You can hold it where you like. Luck. Enjoy.