Martin - is your 16 bore choked?
; If it's choked, measure the tightest spot and use a ball as close to that as possible.
; The .570" ball, about 270gr. weight, is commonly used in 24 bore rifles and is a mite small for the 16 bore shotgun.
; I suspect a 20 bore ball might be better sized and much heavier. The 16's nominal size is around .665" or .675". Lyman makes a .662" RB mould. Even with a full choke, the .665" bore would reduce to .625", leaving all the moulds in the .600" to .625" range open for use. Lee makes a cheap RB mould in a couple sizes in between these. .600" and .610" at least. These balls weigh in the 320gr. weight range.
: As the bore size gets smaller, I tend to look toward the heaviest ball I can use in that bore. In a choked gun, that would be whatever 'just' fit the choke.
; If you are stuck with the 24 bore ball, OK, use it, but don't be surprised with the lack of smashing power we've come to expect from the larger bores.
: In actuality, the .570" ball will probably do just fine for most game this side of Africa.
; One thing's for certain, with a bit of handloading work(and a chronograph), you could get some prety fine speeds with that light a ball.