Qn abt infighter and gunslinger

according to wat i know, a infighter will gain appro. 2times hp of a infighter when lvling normally ( not hp washed e.g.)

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any1 knows if the "according to wat i know" part is correct?? or if im wrong??

I'll tell you right now, that an infighter does not gain anywhere near 2 times the hp of an infighter.
Probably around 1.1 ~ 1.2. ±0.1. Somewhere in that general vicinity.