I have a different chart that agrees on the sizes of the smaller buckshot, but says the 000 is .360". I would go with the Hornaday chart. #1 buck, with a good patch should work well in a .32 rifle. If you want a really tight ball to barrel fit, then order the #0 Buckshot.
All commercial shot is made with antimony to harden it. There are trace elements of other metals, but lead and antimony are the primary components. They may require a firm rap to start down the barrel, but this is a small ball- 45 grains or maybe less, 65 grains in .36 caliber. You are not going to hurt your hand smacking a short starter to get these small balls going down the barrel. The tighter fit will insure consistent accuracy, and better chamber pressure, and burning of the powder in the barrel, so you don't have cinders and unburned powder in the residue to clean out.