I was given a bunch of old reloading stuff a while back and throughout all the boxes of stuff were several loose rounds of old ammo. One is a small .22 centerfire and I think it is a .221 Remington Fireball. I say think because it is not marked but matches the size and configuration in a reloading manual with actual size pictures. The interesting thing is the headstamp is 'TW" which is the mark of the Twin Cities Ordnance Plant, Minneapolis, MN. I was wondering why a Mfg. of military ammo would produce the .221 Fireball, unless there was a military use for it. Any ideas?