[Wildwilley]

RWS makes a good cap.
It's a magnum cap and will change your group a little.
It makes the gun go off a little faster.
You also might have a light spring. If thats the case, you can contact the manufacturer and get a new one. They usually cost about $25 and they're pretty easy to install.
If your spring is light. You can also try shimming it.
That is placing a small piece of steel in between the fold of the spring. This you will have to do carefully cause it could break the spring.
Place the shim in the fold and pull back the hammer. If it's hard to pull back, lay off the pressure and re-plaace the shim.
I bought a CVA Missouri rifle a few years back and couldnt get a spring so I shimmed it and it has worked fine for 9 years.
L&R has started making drop in locks for some of production guns.
You could go that route. I use L&R and they are strong locks.