Ditto

A few of the local guys shoot 28 bore smoothbores and usually use from .526" ball (Lyman mould) to .530", which allows some latitude in patch thickness.

Normally in a smoothbore that is firing solid shot we strive for a ball that is .025" to .030" smaller than the bore, especially in the larger sizes.

The use of this size allows us to use a thicker patch which is easier to load in 'original' barrels by having more compression capability and holding more "lube' to keep fouling wet.