Replacement hammer spring (also sometimes called main spring) for the FX Impact air rifles (Including Impact X), Impact MK2 and Impact M3

For FAC / high power: Select part 11500 – Same spring for all calibers including FAC (.177; 4.5mm, .22; 5.5mm, .25; 6.35mm, .30; 7.62mm). This is the lower (shorter) spring in the picture, however is the stronger of the 2.

Factory Spec Power Plenum Model: Select Part 2604. This is the same as the FAC spring above but a little shorter 52mm. It is the one that comes as factory standard on MK2 ‘Power plenum’ versions (Not pictured)

For UK limit Sub 12ftlb (all calibers): Both versions of the spring have been used in the UK spec models. The most recent use the softer but longer spring (16024). Many customers have noticed improved sub 12ftlb performance with this spring when fitting to earlier versions (which used the shorter 11500). If you change the spring in your rifle to a different version than supplied originally the power may change and the regulator pressure may need adjusting to attain the correct power levels.

Part number A36 on the parts diagram for this airgun.