Since speed isn't a problem I don't see why they can't just simply dodge the bullets, assuming they are 1300 m/s they should be able to dodge a bullet when it's 0,5 m from their face and still have problems when they bullets are shot from several meters when all it's needed to dodge them is a low end supersonic reaction.
I never mentioned this but I guess I will at this point, in Tenjiku arc when Tenjiku lost and they could reach Kisaki
Hanma saved him escaping with a motorbike and Draken in order to follow him used a motorbike, if the verse has a supersonic+ MS as shown by the calc I really don't understand why Draken or Mikey just didn't teleported in front of the motorbike since they should be able to se it as frozen in time + Mikey every time he has to go where his gang is to fight (Moebius and black dragon arc) he just doesn't run there since he only needs some seconds and he will just save the situation, still he waits for them to fight, Ik what PIS is and well motorbikes and guns are consistent within the verse from the start to the end of the plot, a PIS is when a single moment in the narrative contradicts the rest... but when the narrative, from the first to the last arc, is consistent and the only things which is contradicted are your calcs then the calcs are an outlier, I hope you don't think calcs (which are basically fanmade) are superior to the whole narrative.
If the verse was legitimately supersonic or higher I don't see why the author never showed sonic booms or just didn't make them dodge a bullet or run a km is some seconds.
In less words the characters can't outrun motorbikes (probably only Angry and Izana can) and can't dodge bullets so their MS and reaction are limited and the AS of the verse is nowhere higher than the reaction of the verse since people can react to the fastest attacks of the verse and still have problems with guns, it is just that, tomorrow you can bring a 20000000000000000000 m/s calc it will just contradicts the consistence of the plot and there is nothing you can do about it.
If calcs are gonna come up I'll probably make a thread in order to set an outlier for the speed of the verse since their limits in speed are clearly shown and I bet you will just try to prove with your interpretation or with calcs what is blatantly shown in the manga, the characters are slow, they display an inhuman strength and not an inhuman speed.
The only way I see to have a supersonic+ speed is to downgrade the intelligence of the verse, your choice.