Your Minie-bullets with a (coarse-threaded) hole into the nose are "wormed" bullets, because the soldier used a Bulletworm on the end of the rifle's ramrod to unload the rifle by "pulling" the unfired bullet. See the photos below.
Explanation, for anybody here who doesn't already know:
Most civil war rifles were Muzzleloader firearms, meaning, the bullet was loaded into the front (the muzzle) of the gunbarrel, and the rifle's ramrod pushed the bullet down to the back end of the barrel (the breech). The only way to unload a Muzzleloader is to somehow pull the bullet all the way back up the gunbarrel and out of the muzzle. So, the soldier would attach a "bullet-worm" onto the non-rammer end of the ramrod, insert it down the barrel to the bullet, and twist the ramrod clockwise until the bulletworm screwed itself deep into the soft lead bullet's nose well enough to grip it and pull it back out of the gunbarrel.
As the photos show, there were two forms of bulletworm.... one shaped like a tapered coarse-threaded screw, and the other shaped like a DNA-style "double helix."
One of the photos shows an incredible rarity... a bullet which was fired while the ramrod (with bulletworm) was still in the rifle's barrel.
