I heard they will send you a sample pack of different sizes to fit your gun.
I got the sample pack. The weird thing is I was able to get all of them down without much trouble. Including the biggest .503. Not sure why the bullets were so much harder to load than the sample pack bullets? I ordered more bullets and am trying to find some BH209 but Sportsmans is the only place close to buy it and of course they're out of stock.