You're using a 430 grain bullet?!?!?!?
Couple years ago (has it been that long?) when I bought my 76 in .50/95, I first tried a shortened Lyman 515141 mould that I had cobbled up for my 42" twist .50/70 Sharps Carbine.(original 1859 barrel - lined and chambered by Sharps)
"The shortened #515141's, weighing from a low of 410gr. to a maximum of 420gr. I lubed them by hand, with a mix. of 60% (good) beeswax, 40" Vaseline which had worked for me, for 20years or more, smokeless or black powder. I made 2 deliberate, 5 shot groups, off the bags (resting the back of my left hand on the bench-rest's bag) ran a horizontal group 3 1/2" wide C to C and only 1 5/8" high, then the nasty, gusting cross wind shifted, to directly behind us & gusting making a group 2.9" C to C and only 2.3" wide."
This was the only time I have deliberately shot paper with this rifle. I have since mounted the Smith Enterprises ladder sight I pictured on a previous page.
With that sight & the 44N powder load f 52gr. + 368gr. Lyman 515139 (1,650fps), I got into the dirt underneath our 1,000 meter buffalo.
This was after hitting the 200 and 300 meter 16" x 14" AR500 plates. I ran out of ammo and promised myself I'd hit that buffalo this summer. I have some ammo loaded (same load) and a rough idea where to set the slide and yes - it is near the top. Have to be careful or the heal of the butt really digs into the collar bone.