.454 balls will also shave a good bit and I have never had a problem with them, and is typically
what is recommended in most user manuals. The .457 is typically used in Ruger old Army's, but can certainly be used- they just aren't usually stocked in most local stores if you have to find them, and the little shaved ring is a bit stiffer and must be removed or it will bind the cylinder in the barrel/cylinder gap. I can't say that I've used the .457 balls I have yet...still waiting for a $100 stainless old army.
The .451 balls may or may not be a good snug fit, depending upon the tolerances of your cylinder. Alway err on the side of going up a size to get good accuracy and to help prevent chain fires.