Neil Price is fet­tling the trig­ger of an al­ready im­pres­sive ri­fle

Air Gunner - - CONTENTS -

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.

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