F.I.E. (Firearms Import Export) company were never much for real quality in the firearms I have seen from them. In fact I own a F.I.E. .45 caliber long colt derringer. It will shoot a .410 shotgun shell out of it. Not the nicest looking piece in the case, but it does shoot and do what it was intended to do.

You will have to test the barrel to see what twist it has. That will help you decide what kind of projectile it should be shooting. As you pull up a tight fitting patch on a jag head, the rod will want to spin. Make note of how far it spins in relation to the distance the patch travels up the barrel. This will give you an indication of the twist. I would personally guess it is a roundball twist.

If the rifle is as old as you suspect, it is probably a 1-66 to 1-80 twist. Most of the old rifles came with roundball barrels. Also the older rifles usually had a max load of 100 grains of 2f black powder, so keep that in mind when loading the new powders on today's market. I personally would not use Triple Se7en in that rifle. That powder had a different pressure level then other powders. Your rifle being a .45 caliber would probably like 3f powder better then 2f, so I really have no idea what the max charge would be.

I would try it with 50 grains of 3f and a patched roundball (and work my loads from there). It will be interesting to hear from you on how the rifle shoots... Good luck with the rifle.