I'll try this time, I was just too darn excited to pay complete attention to all the little details! smile Good to know to fire both barrels as soon as possible one after the other; I definitely paused a bit between both shots on the first one.

IMO the barrels are quite thick and the chamber walls are as well, so for whatever that is worth, I'm not super concerned in that area.

I am also planning on trying to measure the twist rate of the rifling; was twist designed/designated in X twists per foot at the time this gun was manufactured?

I was also considering if the bore is too slim for an actual .366 diameter bullet, pulling x74 bullets then resizing via a push through sizer and reseating may alleviate any continuing pressure issues while also providing an easy and readily accessible way to load 'custom' ammo with out too much fuss or extra expense. Of course accuracy may be insurmountably effect by lengthening the bullet.

Also for a frame of reference, do you have any idea where the charge specified on the chambers stacks up in regards to hot loaded, middle of the road, or light loads?
3,5 g G.B.P./St.m.G.