i have had good luck getting liners and carbon sleeves from utah airguns and all of the guns in stock are probably not worth buying most are fx copies now days
they are total junk i had one in .30 cocking effort was so high it wouldnt index themag correctly !! wasnt fun to shoot everyone said send it to bwalton to mod it wasnt worth it 750 for the gun another 300 to mod it sold it and bought a fx
i bought a hatsan carnivore it was a pile of poop so hard to cock wouldnt feed correctly etc it was nearly 800 bucks sold that pile and bought a fx whisper !!! never had a issue with it for 100 bucks more