Please accept my heartfelt excuses for letting you wait so long!
Here are the answers to your qestions concerning the measurement data of my two tiller guns.
The measurements of the bronze barrel tiller (stick) gun formerly in my collection, late 15th century, are:
overall length 146.8 cm, barrel 56.6 cm, caliber 13 mm (measured about one inch back of the bell shaped muzzle opening widened for easier loading).
The data of my wrought iron barrel, with remains of its original tiller stock preserved in the socket, ca. 1450-60, are:
overall length 72.7 cm, barrel 56.1 cm, caliber at the widened muzzle 20 mm, narrowing to ca. 16 mm after about one inch (see above).