I haven't tried the above method, except for in my .50/70 Sharps, however, I breech seated the bullet then shoved in a case full (80gr.) of powder behind it.

This load was possible with the overly long 1867 chambers Sharps put in the caplock to centre fire conversions. Their chambers were 1.9" long, not 1 3/4" which was standardized in 1868 for the rolling block rifles.