Steve,
I stand corrected that it is 10 thou per wall. Not thinking this morning.

I have a Birmingham 12 bore, maybe 1880 with jug chokes that I measure as modified and it is very effective on long clays out to 50 yards. Those of you who have been to rock Mt Sporting clays in PA know the birds that come off the cliff and that is where this gun excels with 15/16 oz., PB, CB wads in Rem hulls. I use plastic wads with no ill effect.

So many guns, so little time!