Haven't run the numbers but "Modern Breechloaders" gives

12 - 0,729" - 0,720"

13 - 0,710" - 0,700"

14 - 0,693" - 0,690" - 0,680"

15 - 0,677" - 0,670"

16 - 0,622" - 0,660" - 0,650"

17 - 0,649" - 0,640"

If I remember correctly, both the Austrian and Brits used a solid projectile on the 1st pass and shot later if the tube was destined to be a scattergun. Not sure when or if the Brits ceased.

Kind Regards,

Raimey
rse