There are two other possibilities,one is that not all 9mm brass is the same thickness it can vary as much as .003" between brands. If you revolver chambers have vary tight tolerances it possible that case dimension is giving you the problems. I have a Ruger 9mm revolver and anything I fired in it both hand loads as well as factory ammo drops right in. I have had on a few occasions a few rds. that were tight but they did push in with a little thumb pressure.
You might want to mic each one of your cylinders as well as several brands of loaded ammo at the web and see where the difference is.
Tolerance is not liking people from other countries...
All manufacturing and all manufacturers require 'tolerances'. That is to say, there is some difference in measurements from one brand to another and from one lot to another. This includes both firearms and ammunition.
Most of the time it all works fairly well, once in a while one finds a firearm of 'minimum' size' and ammunition of 'maximum' size. Then it doesn't fit right.