Re: Subsonic .22 Ammo
much like the above posts, it is common that one ammo that is fantastic in one rifle (even the same manufacture and model) seemingly does not work as well in another. best thing is to invest in many ammos up front, test them at different distances, and pick the one that works the best for what you can afford and buy a whole bunch of it.
remember the stuff that works great at 25 & 50 yards may not work as well further out as stuff that didn't work as well at the shorter ranges.
so also pick an ammo that performs at the distances you'll mostly be shooting at the most, or if shooting multiple distances, gives you the best consistancy throughout ALL those ranges.
Also as mentioned before, the subsonic / match / standard velocities do not go through a transonic change keeping the bullet more stable from 0 to infinity distances which contribute to it's accuracy / consistancy vs. high velocity.
depending on temp, altitude, etc. and shooting shorter ranges, there are bulk high velocity rounds (CCI Blazer for example) that performs as well as "higher regarded ammos" in the subsonic catagory.
remember that match / standard velocity ammos are technically subsonic as they are generally under the speed of sound throughout their flight.
so yes in general terms, subsonic ammos are more consistant.