I am no expert on the 99s , but my .22 cal version shoots rea nice with the standard set up. I have a very nice barrel weight in blued steel on my gun and it as tamed the hold sensitivity for me.
Dm80 on this forum does some very nice mods and barrel weight's.
The.22 guns are generally less twitchy at the 11+Ft/lbs.
Atb
Les..