Eric,

If you could post or send a photo, it would help.

The P53 Enfield sight was graduated to 900 yards (the last version had sights to 1000 yards, but these were not general found on guns sent to the US/CS). These marks were 2-3-4 on the side of the sight base, and 5-9 on the sight leaf.

P56/58/60/61 short rifles had longer range sights, up to 1250 yards. Anything more than this, would not be a standard Enfield sight. Maybe some sort of non-issue private-purchase long-range target sight, or a sight for a later type of arm.

This doesn't sound like a Civil-War era Enfield sight.

Geoff Walden