It is difficult to tell from the picture, but this rifle appears to have a round barrel from action to muzzle. The reason I bring this up is the fact that most, but not all 43 Spanish rifles has a short octagon section just ahead of the receiver. Not having the octagon section does not mean that it is not a 43 Spanish. If it had the short section, it would be a good bet that is is a Spanish.
Your comment about a good bore would leave me to believe it is probably not an Egyptian. I am sure there are some good Egyptian rolling blocks out there, however I have not seen one. Everyone I have seen looked like it had been dragged behind a camel for about a hundred miles through rocks and sand. Actions were in very rough shape, bores were even worse.
Most Spanish Rolling Block are in surprisingly good shape for rifles of their age. I have seen a few that appeared in new or near new condition.
The 43 Spanish and 44-77 Sharps and Remington are extremely close in chamber dimensions. Both are bottleneck cartridges. They are among only a handfull of blackpowder bottleneck cartridges that don's cause severe fouling in the neck and throat area. This fouling affects accuracy and the ability to chamber another round.
You will find the serial number of the rifle on the side of the upper tang (most of the time). Remove the tang screw and the butt stock will just slide off the action. If the tang is not too rusty, you should be able to see the serial number.
If your rifle has a good bore and the action is tight you will have a lot of fun shooting this rifle as is.
You can get brass (possibly loaded ammo) from Buffalo Arms, Sandpoint Idaho. Reloading dies, bullets, also available from them.
Have built several custom blackpowder rifles using rolling block action. They make super rifles using the old calibers. I shoot probably 1500- 2000 rounds a year through mine.
