Join Date: Sep 2008
Location: Bavaria, Germany - the center of 15th and 16th century gunmaking
The touchhole is on the right hand side of the cartrigde so that its position is within the pan where the ignition takes place, just like on any 'normal' barrel.
As I tried to point out in my thread, for as far as we know from similar 'cartridges' or exchangeable breeches preserved still loaded (I posted one specimen here), we can tell that these insertable devices only contained the powder measure and plug, while the ball was separately shoved into the rear opening of the barrel before inserting and closing the breech shut.
The measurements of the Passau arquebus are:
overall length 107 cm
barrel length 78.9 cm
length of lockplate 35 cm
caliber 1.5 cm
cartridge: length 7.8 cm, outer diameter 2 cm