Not really sure on overall ballistics , he uses it on 12” plate at 100yds. I’m loading a light load to preserve the brass and firearm.
Nice little write up for those not familiar with the 43.
https://www.blackpowdercartridge.com/thoughts-on-the-43-spanish-and-the-remington-rolling-block-rifle
43 Spanish is the second one. Brass is a stinker to come by for the old rolling block. He found 20pcs of Bell Lab. brass awhile back. I’ve made brass for him out of 300 Wby in the past.
Just a wee bit bigger😁
Bingo , he has a pair of the old Enfield 303s.
The left one case doesn’t fit any of my loading blocks. Years ago I made a 20 round plywood block for it.