@Nikosgarofola You have a big misunderstanding about bullet, a normal ball round is much better at penetration.
Hollow point is designed to increase its mushrooming effect making it very bad at penetration but maximizing its stopping power, this will also minimize the collateral damage from overpenetration. To put it simply, put aside soft armor, it's not even meant to overpenetrate an unprotected body.
The bullet used was just a simple ball round, more than that, the rifling on the bullet could mean it has considerably large caliber, thus it was necessary to reach or maintain ideal rpm.
You're right about one thing, as it is, Senku is without doubt dead.