I suppose you mean the calibre? Probably because the difference between the two rounds is marginal. For your other questions: Flak, as in MAA and SAA are, right now, in an extremely good state.
Throwing knifes are a gimmick as is melee, but yeah you usually do not kill a guy with one stab. Hardcore is not very likely, as DICE does not want to separate playerbases.
How does a sniper spam ADADADADADADADADA for 25 straight minutes, while still taking perfect headshots across the map? How does an assault ADS while running and jumping and in mid air and killing the opponent? How does an 88mm tank shell deal less damage then a PIAT? How??? So many questions, so little sense.
How does a sniper shot to the chest do less damage than 2 SMG shots to the leg?
How does a full PDR tank round only do 80 damage?
How does a HE tank round not kill someone that it hit directly or it landed next to?
How does a flak cannon still take 3-5 shots to kill a single infantry?
How can flak cannons and mobile AAs not kill sandbags and walls (IRL, those bullets are as big as my forearm)?
How can SMGs, ARs, DMRs, and MMGs have the same accuracy and faster TTK than snipers at range?
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Balance is entirely dumb. Why is the minimum damage for everything a 3 shot kill? Oh, except for pistols and everything by a tank.
How did my tank get one shotted When it had full health on the tank playing conquest on devestation? Yes my tank was destroyed in a single explosion with full health.
Possible. Funny thing is NEVER get in tanks. That was my first attempt in BFV with already 40 hrs of playtime in and I helped kill one tank then I was destroyed 30 second later. And that is why I don’t get in tanks. Haha. At the time it was a WTF moment that made me want to quit.