Load for this?

[Turtle]

 A friend has this original gun and wants to shoot it. It is sound and safe, but 42 1/2 cal. and how would you ever seal those deep(.030) narrow groves with a patch? how did they shoot these things? I told him to hang it on the wall.

[MuskratMike]

Yep, hang it on a wall. My wall!

[Longknife]

Turtle, A a lot of those original barrels had the rifling and lands filed (coned) at the muzzle to allow for easier loading..,,,,Ed

[Pukka Bundook]

Turtle,

What Ed says above, plus;

Hanging it on the wall is not a way to find out how it was loaded originally.   It Would be used  at one time, so likely can be done so successfully.  :-)

I always find it V interesting figuring out how things were done, as done they were. 
I'd start with a thick patch with decent tallow type lube, and not worry about the ball being a tad small.  The patch should ram into those grooves.
Keep us posted on how he does with it!

Best,
R.

[rich pierce]

Here’s what I learned from guys in my shooting club regarding unknown original barrels. Unbreech it and clean it as best you can then run an oily patch. Using a plastic or copper mallet pound a large ball into the muzzle. I’d use a .490. Trim off the flattened flash, short start it, and drive it all the way out through the breech with a steel loading rod. Now from the slug you really know the dimensions and condition of the bore.

[Brokennock]

What if you used a patch that was reasonably tight to engage the rifling, without worrying about sealing the rifling from gas blow by, and use a lubed wad between powder and patched ball to get a gas seal?

[Lobo]

The muzzle of my .62 Jaeger

[Turtle]

 Those groves look the same depth all the way to the breech. I pulled the breechplug to check it. Good solid threads and tight. Bore not too bad. I agree, it would a fun project to experiment with, but I don't think that is what he had in mind. He just wants to shoot it. To begin with it would need a custom made .415 mold.

[Daryl]

First thing to do for me, would be to either lead lap it, or cut a square of Scotch Bright on a jag, - the maroon colour, then with some WD40 on it, run it lengthwise about 100 strokes, changing the material as needed to maintain a tight fit.
This should smooth it up to the point you can really tell what is going on in the bore.

LOBO- VERY nice filing!

[ron w]

turtle, if you look closely at the groove in the 10 o:clock position you can see the ramping of the grove from being filed for loading. further back into the bore you see that the rifling looks pretty much conventional in depth.  the idea is that the patch fills the deepened groves and then gets compressed into the normal rifling as it gets pushed down the barrel. this forms a denser harder "fin" of  compressed patch material that follows the rifling when shot. it also helps to wipe the rifling clean a bit both as the ball is pushed down the barrel and when the ball is shot out under pressure from the load.

[JohnnyFM]

Lobo,
Beautiful job on the muzzle!

[Daryl]

turtle, if you look closely at the groove in the 10 o:clock position you can see the ramping of the grove from being filed for loading. further back into the bore you see that the rifling looks pretty much conventional in depth.  the idea is that the patch fills the deepened groves and then gets compressed into the normal rifling as it gets pushed down the barrel. this forms a denser harder "fin" of  compressed patch material that follows the rifling when shot. it also helps to wipe the rifling clean a bit both as the ball is pushed down the barrel and when the ball is shot out under pressure from the load.

Enlgarged the barrel considerably by clicking on it a couple times and the lands are also filed out(evident at 9 and 11 o'clock), just about to actual groove depth,
 with even heavier filing in the grooves.

[Turtle]

 I slugged the barrel-.425 on the money. the groves may be shallower at the breech end, but the deterioration makes it hard to tell.

[Daryl]

When the picture is enlarged, you can see the actual groove depth (comparison) in the 10 o'clock area.

It is very shallow compared to the muzzle's face.