Never heard of an M-500. What’s that, a hand grenade?
I remember as a kid shooting Cherry Bombs out of a Wrist Rocket slingshot. Man them suckers went far.
Never crossed my mind though what would have happened if it had been a ‘’short’’ fuse.
The M-500s were American made, with the power of (about) a quarter stick of dynamite.
Water proof and easy to light from a central fuse. Bright red, about 6 inches long and one inch thick...