[haggis]

Welcome to the forum. Would it be possible to see clear, close-up pictures of the markings on the left side, including the caliber marking on the barrel? This gun might be a refurbished NS, with caliber changed from .455 Eley to .45 Colt, and with British proofs from British service in WWI. Or maybe not. Anyway, if you can post photos, perhaps we can infer more.

Buck

 

[haggis]

The gun was originally .455. There is a slight recess cut for the smaller diameter .45 Colt rim (it's thicker than .455) so it will headspace correctly. Both cartridges can be fired in a cylinder so modified. Accuracy with .455 may suffer due to the long freebore caused by the extended .45 Colt chambering.

The top mark on the top of the left frame is the British "Broad Arrow" property mark, so the gun was a service weapon. The original caliber stamp was "New Service .455 Eley" which has been partly obliterated, and left with just "45" to indicate a caliber change to ".45 Colt" (and is not a really good way to indicate that). I know the crossed flags on the cylinder mean something, but I don't remember exactly what. At one time each cylinder chamber was also marked with "crown over whatever" proof to indicate proofing for release for private sale. It also looks like the "pony" is still partially there.

Buck

 

[haggis]

What ammo would you all suggest? Would Hard Cast be ok?
PsTaN[/COLOR]

I'd stick with moderately soft bullets. For the pressure that you will be shooting (mild loads) you only need BHN of 8-10 - this is roughly 2%-3% Tin. The higher the chamber pressure, the harder you need. Go too hard, and the gun will lead from a different mechanism - blow-by from failure of a hard bullet to obdurate to fill the bore. You can get leading from too hard or too soft - there's a sweet spot you need to hit.

Buck