Everything ammunition! What to use, where to get it, surplus ammo headstamps, the science of reloading and more.
550 is manual indexing, it’s a great machine and is very versatile and robust. I have one that I use a lot and have it several caliber changes. I also use a 1050 for the calibers i shoot the most as these machines are great but caliber changes are slightly difficult and time consuming plus very expensive. The 650 and 750 are basically the same machine but the 750 is the new version of the 650, they did away with the rotary priming system and use a more reliable slide style like on the 1050 & 550. They are all good machines. If you plan to reload several different calibers I would go with 550 or 750.