The FX STX pellet liners can be purchased for Smooth Twist X barrel systems only. You can upgrade from the standard Smooth Twist liner that is only rifled at the last couple inches, to the A liner which fully rifled and designed to shoot standard size pellets mentioned in the short description above. Another option would be to purchase the B liner which is geared more towards the heavier pellets that have non standard head and skirt sizes (also detailed above).

*Only compatible with Smooth Twist X barrel systems found on newer rifles*