The original Civil War era Enfields (and Springfields) had the sights calibrated for a pointed Minie Ball that was a good deal lighter than the bullet you're shooting, Gatofeo.
I don't know the exact weights, but I suspect it was more in the 450-475 grain ballpark. I expect some of our Civil War experts will know.
You can get Minie Ball molds from Lee, pretty inexpensively.