Either or is good. I mean I use .25's outdoors so for CAPS you're probably good with that however at the same time .28's should give you a tighter grouping even if they travel slower it's not like theres that much of a difference since the distances to the targets are so short.
In short .25's are probably good enough but .28's are what you should probably be using.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE