Great piece of brass!
The original post shows a 12 inch barrel Pietta buffalo or sometimes called Bison. They are fantastically accurate and I routinely shoot mine at 40 yds. If I sit on my butt and rest the barrel on my knee, every shot will go right in the black on a 25 yard target. It holds 2 1/2 groups easily.
I use 25G FFFg and it is plenty of powder. As far as the brass frame, it will hold up just fine with normal loads, I have been shooting mine since 1986!
The only problem I have had was having to replace the "Hand". it plain wore out after about 3000 shots, but I will take some of the blame for that, as I tend to really yank back hard on the hammer when shooting fast.
One of the most accurate charcoal burners I have and if I had not been able to repair and replace the hand on mine I was ready to go buy another!