SMK CP 1 and 2 Longer Stainless Bolt Probe and larger Bolt Handle for .22 or .177 the .177 is made approximately 1.5 mm longer. Clears Transfer port for more power and accuracy.
To get the best it is best to have a cleaning rod, then to take the barrel and breech off. Place your favourite pellet in the breech and push forward while looking underneath to see the progress of the pellet. You want it to just clear the transfer port for maximum power. If the pellet goes 1 mm past the transfer port then remove 1 mm from the front of the nose of the pellet probe.  Don't forget that it may be different with different pellet designs.
A 15.5mm bolt Handle in Stainless steel is included.