What are these projectile? And what fired them?
Parker Hale made/makes very nice quality replicas of percussion firearms. They have made several types of .577 Enfield. Since they are in the market focused on American Civil War era guns, they added the Whitworth rifle (with hexagonal bore) and also .451 caliber Volunteer rifles- essentially a match version of the .577 Enfield in smaller caliber, and considered by some to be a Civil War sniper rifle.
I believe the .451 bullets you show are for the Volunteer rifle, but can also be used in the Whitworth, if the shooter does not have a hexagonal bullet mold handy.
Pedersoli also makes the Volunteer rifles today.
Here is a link to a video about the Volunteer rifles, with quite a bit of good history on their place in history merging military and civilian rifle shooting, the origins of the British National Rifle Association, and then detailed description of the entire sequence of serious target shooters loading for best accuracy. There is a lot more than just bullet, powder and cap involved. (Hey, more collecting opportunities!). The narration is a bit slow paced, but worth it anyway.
You can click through the annoying ads.
Thanks. Love that marching music!!! I made an offering to Gods for inventing all containing cartridges after watching the video.
Whitworth chambered to take hex. and cylindrical bullets and in his time, he offered both types of ammunition. In the amount I’ve seen of it, the cylindrical ammunition is much more common that the hexagon type.