Just a few observations/tips from a guy who buys and shoots 50,000 pellets per year. JSB and H&N pellets are the best. Do not interchange brands once you find a pellet that works well. Different lead alloy deposits in a barrel may degrade accuracy until you clean the rifling with ‘felt’ pellets.
If accuracy suddenly goes sour with a springer your scope went bad and your mounts are possibly shifting also. Springers eat scopes. Some scopes (Hawkes) are springer airgun rated) and will survive a longer period of time. PCP airguns don’t abuse scopes.
.22cal pellets are vastly superior to .177cal pellets on varmints. 750-800 fps gives you accuracy, clean kills, without muzzle bark. A 40 yard zero is a good place to start. Then test at 10 to 80 yards and tape the drops to the side of your scope.
If you ever catch the airgun bug then treat yourself someday to a HW97 or AirArms TX200. Do it before you get too old to operate the underlever cocking system. Superb quality rifles, when I was 10 I started with Daisy and Slavia and was grateful to have them into my teens. Now its FX Crowns and RAW HM1000 PCPs.
But never forget or leave behind your springers. A quality German or English made springer will be around to teach your grandkids marksmanship many years down the road. Trust me on this.