...I dislike the fouling from lead-only bullets [.22 Rim Fire], so I would prefer to shoot the copper-plated stuff...
I have never seen any lead-fouling in any .22 Rim Fire I have ever owned. The only fouling I have seen, even from extensive shooting, is from the burned powder/primer. If you are using copper-plated ammo in a .22 Rim Fire to escape "fouling", I think you are wasting your time. If your gun actually "leads", you likely have a rough bore.