I haven't even shot this thing yet..
Rimfire rifles are crazy picky about what ammo they do best with. Yoh can have two production rifles right off the assembly line prefer two entirely dif types of ammo. I believe most of this is due to rim thickness vs headspacing from one rifle/ammo to the next. I have tightened the headspace on my M12 by a few thousandths and it completely changed what ammo worked best in that rifle. I haven't ever weighed my rounds simply because shooting decent match grade ammo it would imho be overkill.
I like....
Eley
Wolf
SK
Fed gold ultramatch
Aguilla match
RWS
CCI standard vel
Norma tack22
There is a bunch out there, but I haven't tried them all. The important thing to remember is... stick to 40gr round nose lead... lubed preferably, and under the sound barrier.