What was the best bullet ever made?

Full size rifle roundThe Chey Tac .408 caliber round, it has the the capability to shoot 2000+ meters and 11000 joules upon contact

Intermediate cartridges

The 6.8 SPC, giving the range of a 5.56, and the ability to release 2297 joules of energy upon contact, about the same as an AK-47

Pistol

.45 ACP, because of it's wide variety of firearms that are capable of firing that ammunition, and the immense amount of energy that it releases.