ben

the 12 bore dbl. rifle was the medium DG caliber of the bore gun days, read sir s. baker on the subject and you will see that he loved the 12 bore and held it in high regard as a do it all gun, sort of the 375 H&H today.
yes the 2,5 can hold 7 drams +, and the full grown 12 bores were indeed the smallest recomended DG caliber when going all over the empire enjoying the sport of hunting.

best regards

peter