yeah but OP was asking if it was possible to lower fps to field legal status, you replied with weight change of ammo which was the incorrect answer regardless.
Changing weight is not to adjust your fps in any way, it's to retain accuracy and consistency to overcome manufacturing defects in the BBs. People don't change weight because they want to shoot slower.
I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.