Bought an old USGI steel pot helmet from the surplus store. Took the cover off and, whaddyaknow, it's BLUE. Perfect.
Hauled it out one day. Had two guns on me; a Winchester 94 Trapper carbine, 16" barrel, .357 Magnum, with 158 grain LSWC reloads, and a 4" 1911 .45ACP, with 220 grain FMJ ammunition. The .357s were hardly "full house" loads; I bought a cheap 300-pack from Cabelas, and got a free ammo can.
Anyway, I set the helmet in the snow, and paced back about ten feet. I shot the helmet from the side with the carbine; the bullet punched through the near side and made an outward dent on the far side. Hotloaded, FMJ .357 ammo would do better. Pointy-tipped stuff even better still.
Anyway, the I shot it with the .45, same distance. The .45 bullet put a much larger entry hole in, cracking the steel a little. Again, it made an outward dent on the far side, but didn't exit.
In any case, I'd rather not have had my head in that helmet.