Need more clues. Measured diameter, length.
I've never loaded a .45ACP or .380 with a concave base.
In my experience, bullets with a concave base were designed to be shot from a low velocity/power gun, possibly a Muzzle loader. The skirt is supposed to expand to seal the round against the barrel to prevent gas escaping around the bullet.
I've never loaded a .45ACP or .380 with a concave base.
In my experience, bullets with a concave base were designed to be shot from a low velocity/power gun, possibly a Muzzle loader. The skirt is supposed to expand to seal the round against the barrel to prevent gas escaping around the bullet.