I'm very surprised by the 587ft/lbs... nice one
What kind of load did you use?
The highest energy I reached (.457/143gr Round ball+pure Black powder(Cap&Ball)):
Rem58: 1182ft/s, 443ft/lbs
Walker: 1430ft/s, 649ft/lbs
Rem58 (carbine/18"): 1488ft/s, 703.6ft/lbs
^^Which I thought was huge...