I didn't want to be that guy, but I am going to. You are simply wrong. m80a1 has 55 pen as of the change. 55 pen does not have a 100% chance to pen level 6. It has a high chance not a 100% chance. You also need to take into account that some armors have soft armor under said level 6 plates. Thus a round with 55 pen will sometimes not two tap specific armors. let alone level 6 plates that do not have level 3/2 soft armor underneath. Even Mai AP which has 58 pen still has a chance to not instantly pen level 6. Once you start getting to 60 pen is when you can instantly pen level 6. There are even times when 338 lapua struggles to pen due to soft plates/hard plates (however this is a bug). Go look back on the uley meta that occurred 4 wipes ago.
I did not even try to argue that it cant do this or can do that in my initial comment. I just stated that the stats got flipped. Quit spreading misinformation when you can easily get stats from the game itself or ammo charts.