RF Muzzle velocity data needed

I’m looking for any muzzle velocity data for .56/56, .56/50, .56/52 Spencers and 17mm Danish Snider.
Any help appreciated.

Be prepared for data all over the place I checked (Google) three sources for the 56-56 and got the range from 936 ft/sec to 1300 ft/sec. No two places agreed. Vic