PTJ has completely Butchered GUN's fighting style by Making him a pure brute who only relies on his Stats instead of his martial arts and it's only going to get worse.
Gun is someone with Immense talent for martial arts. He had learnt Everything about Yamazaki style Kyokushin karate under a month as a child . He knows many martial arts like Kyokushin karate, Tonfas, taekwondo, capoeira , Judo, Aikido (as far we have seen in screen) and is Implied to know Most of (if not all) martial arts there is under the sun . But PTJ just turned him into a Stat merchant who is only this strong because of his Black bones, UI, Blood of Shingen. Gun is much more than that, He is potentially the Best martial artist in the series, but PTJ chose to butcher his character for aura farming purposes. And it's only going to get worse from here, Because Gun (in HFG) was only 19 years old , nowhere near his prime physic . Post prison Gun (prime gun) is most probably going to have Shingen level stats , so be prepared to say Bye bye to whatever little martial arts we have seen from gun , because it's all downhill from here.