FRAG rounds are broken

As i did a few tests with my friend on an empty server I've stumbled upon a few interesting facts about FRAG ammo for shotguns. I've used M1014 with FRAG ammo which deals 20 damage as direct hit + 25 as explosion AoE damage.

1) Unlike most shotgun ammo types FRAGs do deal extra damage to the head (about 200% damage) but only with a direct hit damage, explosion does not gain any extra damage or dont count as a headshot.

2) Explosion can occur without bullet actually hitting the enemy, dealing its 25 damage without any direct hit damage. The round itself travels further away and explodes normaly somewhere where it should've

3) Round can explode multiple times. It explodes every time a dynamic object such as infantry, vehicles or trees are in range. So round shot through 3 trees will explode 4 times. Every time it enters the tree and once after it connects with the ground (seems like leafy part triggers the explosion but does not stop the round) This also works with this weird grating on the locker that i've asked you about. Round just explodes twice

4) Any round that hit sprinting target always (!!!) deals about 40% of its damage, no headshot damage and suppression at all. I have a theory that explosion dont trigger on sprinting targets at all (yet i do recieve full AoE damage if sprinting enemy was close enough for me to get hit my explosion)

5) Some areas of the target's body (like hands and shoulders) also recieve only 40% damage. This also may be that explosion is not being triggered for some reason

6) FRAGs do registrate slower than other projetiles do. It may require some time of client-server communication to trigger the explosion after and if the round connects

7) The round may be desynched with explosion trigger since it is possible to get only explosion damage or only direct hit damage

8) Explosions ignore body armor perk

9) Legs do reduce direct hit damage by 10% for body body armor perk (explosion damage still ignores it)

10) Explosion effects render on client machine so direct hitting an enemy and covering it with thick smoke without hit confirmation from server is a thing. Enemy player will not see any smoke cuz it does not appear if u stand too close to it (if enemy player even saw a hit, it may have missed on his screen)

11) AoE hits on myself do seem to register faster than AoE hits on other players

That does explain a lot doesnt it? If u need any more information to make the case look a bit more consistent I'll be happy to provide it