The weapon is a bit abstract, but I suspect it's meant to be a Russian Model 1856 6-line (i.e., .60-caliber) rifle. The hammer, in particular, doesn't look exactly right, but the Model 1856 had a distinctive hammer which looked more like that than most others of the period. (There was a later cartridge-firing conversion of this rifle, the Model 1856/67, that had the same hammer, but the one pictured shows no sign of having the breechloading conversion parts, which would be pretty obvious even in silhouette.)

Also, the commentary that isn't links is just the dialogue from the picture, first in Russian and then repeated in Japanese, but I'd only be making a machine-translation stab at the rest of it--I think it's something to do with a 60-minute drawing challenge--so I'll leave that for someone more competent to tackle.

Thanks very much for the translation and explanation.