The Morko gonne in the Swedish Milatary Museum is
.69 cal.
I made some cast bronze Morkos , with a .62 cal for safety reasons .
When it comes to ...proper cal. ... I can garrentee eveything from .50 to 1.00 was used
Years later flintlocks were usually sold with a mold included ,often .43 or .52 ... whatever the bore finished up at.
Gary