You know a better way to master trigger control?
Years ago, several IPSC pals and I took a level 1 Olympic pistol course. We shot air rifles in a convention room at the YVR airport hotel. We learned more in 8 hours of instruction than had we expended 1000 rds of live ammo on a range and learned nothing.
They recommended something they called "wall hanging" - you took a sight picture on a blank wall (no target) and made the best possible trigger pull. Olympic pistol shooters do this for hours as it costs no money and can be done anywhere while travelling where you can have the gun in hand.
Obviously, if your gun does not lend itself to dry firing without damage, this is not recommended.
To say that we got 'fine tuned' would be an understatement. I teach it to newbies before allowing any live fire.