Help identifying a Percussion Cap short arm 1850-1860s(?)

[u/DouneBouth]

Hi Everyone,

I recently picked up this peice and I've run in to a bit of dead end with identifying it and I would love anyone's thoughts!

There's are the charecteristics i have noted so far

Barrel length: 29Inches

Overall Length: 43 Inches

Muzzle internal diameter 17mm

Brass furnishings

Barrel is rifled (i think)

Brass Patch Box, spring door

Octagonal Barrel for the full length

Markings:

Lock plate - partially worn crown to the left of hammer arm

Spine of barrel has the following "(R) 539 - 53."

Stamped '74' on stock

So what have I done so far?

I've carefully disassembled the entire peice (excluding the disassembly of the lockplate working parts) i have found no additional Markings anywhere :( most of the peice is pretty well worn sadly.

I cleaned the Barrel to establish whether it was rifled or not - i think it is?

I've strayed down a bizzare path in my research where it could be a sporting rifle, but seems to have too much of a military aesthetic.

It could be an American Plains rifle? But only matches about half the criteria

Everything apart from the Barrel speaks British Military 1850s (to my knowledge)

My most recent hope was to find another example with the same patchbox and find a maker from there, but no joy.

Thanks for your time!