That is a .50 Cal muzzle loader pistol, They were shooting 35 grains of true black powder if I remember correctly.
They shot 50 Cal Muzzle loader Rifles, 50 Cal Muzzle loader pistols (both cap lock) and a variety of 20 gauge shotguns.
In the picture with both boys one is priming the fire arm for the other, we did that with all the muzzle loaders. (not fully charred unless pointing down range)
These two boys earned their Hunter Ed asst instructor, 4-H asst Hunting coach in one weekend. They are Firearms instructors (4-H) for rifle, shotgun, Muzzle loader and Archery.
The young mad who was capping the pistol also completed his Texas Youth Hunting Program asst Huntmaster earlier this month.
I am proud of those two young men.