I purchased this gun new from AoA about three years ago, Ernest Rowe wanted to see if I could adapt a FX STX liner to this gun so I used a .22 500mm STX liner, made an adapter out of stainless steel that looks just like the factory Bantam barrel on the end but the liner slides inside and is held in place just like any other FX liner.I did nothing to modify the Bantam Sniper at all The gun comes with factory barrel and shroud assembly as well as a FX 500mm assembly. To change just loosen two set screws at top of action, slide out assembly, slide in other liner and snug screws down. It's that easy. I am a Tool & Die maker and have a Hardinge Lathe so everything is made correctly, nothing is half assed. The factory LW barrel is around 420mm long so the 500 STX barrel gives you more velocity. Gun loves most weights of JSB pellets.Has fully adjustable Huma regulator and hammer tension adjustment. Right now gun is set to shoot 18.1 JSB exacts around 900. Price of $1000 OBO , CONUS, will include both fully shrouded barrel assemblies plus two magazines in original box.