.22 Edgun Leshiy low velocity

I'm having some problems with my Leshiy .22 (250mm barrel)

According to the videos I've seen I'm expecting 244 m/s with JSB Exact Heavy. I can't get over ~230-233 m/s. I'd like to get that tittle extra velocity. But when I'm turning the hammer tension spring the velocity pretty much stays the same but the gun gets louder and is consuming more air.

What can I do to get those extra m/s? The only thing I can think of is to increase the regulator pressure a little bit. Could that be the way to go?



Best regards
Incite