I've had one in .45/70 since 1990. Mine is the older, Trail Guns Armory type with browned barrels that are quite heavy. The newer ones have slimmer, blued tubes from photos that I have seen.

Mine has two individual rear sights, each adjustable for windage and elevation. The rib has two dovetails, one for each sight. I have seen photos of some that have the folding leaves on a base so there must be some variations in production through the years.

Mine shoots best with the 405 grainers, but is okay with the 425s and 460s. The 405s shoot well whether at factory velocities or the higher ones shown below. The rifle likes both cast and jacketed bullets. The 525s spread apart too much (my 1895 Marlin likes them though) and I will not increase the velocities to attempt to bring them together on the target. I am not trying for maximum velocities. The results below might show increased velocities with other powders.

Average velocities out of the 24" bbls.:

1250 fps with a Remington 405 grain JFN Factory Load
1650 fps with a Remington 405 grain JFN
1700 fps with a Beartooth 405 grain HCGC
1730 fps with a Beartooth 425 grain HCGC
1650 fps with a CPC 460 grain HCGC
1500 fps with a Beartooth 525 grain HCGC

I wouldn't rechamber mine. It is nice as it is. It is far less expensive than an antique hammer gun. For the price, (I paid $1,500 with wood, leather and canvas case in 1990) it is a nice hunting double rifle for most things. For more power I will use my soon to be finished Searcy Field Grade double rifle in .450 Nitro Express.