It just won’t group

Greetings,

I recently modified my talon ss :

Added hi flow tank
Added hammer weight
18 in .22 barrel
Shroud

Since the barrel swap, accuracy has taken a dump. With the hi flow tank and hammer weight, it was a tack driver at 40 yards. The pellets are just all over the place. I have been using JSB 18.1 gr.

Any ideas what may be causing this? I’m not the best shot BUT I’m also not as terrible as this new configuration is shooting. I have shot over 250 pellets this far.

Extremely frustrated!