[rskent]

My aunt gave me this rifle. I have no idea what it is. The only marking I can find looks like "AB. Bishop". If anyone could give me some information on this thing it would be great.

[TAKtical]

Multi cal side by side? 12gauge-#2 pencil? Just kidding. I have no idea but it looks awesome.

[SDC]

It's what's called a percussion "cape gun", which combines a rifle and a shotgun into one side by side firearm (they were named "cape guns" because settlers heading to the Cape of Good Hope in South Africa wanted this sort of combination rifle/shotgun without having to carry 2 separate guns). Because it's a percussion muzzle-loader, that narrows it down to pre-Civil War, and the styling resembles the typical "Kentucky" or "Pennsylvania" style of longarm that was made up until the 1840s or so. My books show 2 "A. Bishops" active around that time (one "A." and one "A.G.", the first in PA and the second in NY), but this doesn't necessarilly have to be made by either of those; the hexagonal rifling in the rifle barrel is odd, which suggests an earlier instead of a later gun. I would make sure that it's unloaded (lots of these old guns were put away loaded and simply forgotten about) by putting a rod down the barrels and making sure that it'll reach all the way to the breech pieces/nipples), and then consider a professional appraisal.

[ApacheCoTodd]

12gauge-#2 pencil? Just kidding.
Too damn funny!

No other proofing or import/export marks other than the Bishop stamping?

[Jim Watson]

What is the plate standing up over the wrist of the stock?
At first I thought it was a folding peep sight but it is not right for that.

[snakeman]

that is truly very interesting

[bigfatdave]

how big are the 2 mis-matched bores?

[Vaarok]

German styled combination gun, shotgun on one side and rifle on the other. Fairly common as these things go, generally handmade-to-order and with very little documentation available.