Neil Price is fettling the trigger of an already impressive rifle
Part Two of Neil’s trigger refinement on a friend’s Air Arms S510 PCP
18 A couple of minutes with the wet a lot better. and dry and the surface is looking 19 This is the contact surface where the middle sear contacts the hammer sear. 20 That surface should be a bit smoother now. 21 When putting the sears back on to their pivot pins, I put just a smear of gun oil on the pins. 22 When removing the hammer sear it fouls on the aperture in the action and cannot be removed as it is. 23 With a suitably sized pin- punch and a small hammer, the hammer sear pivot pin can be knocked part way through the trigger housing. 24 Only knock it through far enough to allow the top hammer sear to be removed. 25 The contact surface on the hammer sear before being polished. 26 How the contact surface looks after polishing. 27 The top hammer sear positioned back over the part of the lubricated pivot pin that is still protruding through the trigger housing. The top sear return spring is held down out of the way of the top sear with a small screwdriver until the sear is fully seated, and then the spring is released into its correct position. 28 The hammer sear pivot pin can then be knocked back flush with the back of the trigger housing. 29 With the tip of a small screwdriver I now put a smear of Moly grease on all of the contact and bearing points. 30 The owner of the rifle had picked up a replacement brass trigger from Rowan Engineering and asked me to fit it: Rowan Engineering Ltd. Unit 9, Overfield, Thorpe Way Banbury, OxonOX16 4XR
31 The replacement Rowan trigger just slips over the original pivot pin. The middle sear tension spring and grub- screw can now be replaced. I put just enough pressure on this spring so that the trigger when cocked has just a slight pressure on the first stage. 32 With the 1.5 mm A.F. hexagon drive key supplied with the trigger, I adjusted the front screw to give around 3 mm first travel on the trigger. The rear screw sets the let- off point of the trigger. 33 The later S400 and S500 models have a spring that locates between the trigger housing and a protruding lug on the trigger. This is to give a positive ‘ feel’ on the trigger in the uncocked position. Earlier models did not have this spring and the trigger feels loose until the trigger is cocked. The Rowan trigger does not have the lug on the back to accommodate this spring, so the feel of the Rowan trigger in the uncocked state is the same as the earlier S400 models.
I phoned Rowan Engineering to see if they did a version for this later trigger design with the spring, but they don’t. 34 Before refitting the side plate I tried the trigger with my trigger pull gauge again. The trigger now breaks at a fraction below 1lb and is silky smooth with no discernable creep. 35 The side plate is refitted and the trigger tried again to make sure that nothing is binding or tight with the side plate tightened.
All is good, so we can replace the stock with the single cap- head screw and we are back in business.