Beeman Beeman R11 spring kit

Air rifle headquarters. They should have everything you need . Or you can get a drop in kit from either TBT or Vortek. I myself use A.R.H. Parts not because his parts are any better as I’ve never used the others mentioned. I like his service , ships fast and typically has what I’m looking for at a reasonable price.
You’ll want to get yourself some acetone or denatured alcohol to clean your parts. For lube I use the above supplier for moly lube. ( it’s pricey ) but it goes a long way.