Neil gets to work on a lovely Air Arms Pro Sport to see if he can im­prove an al­ready fine ri­fle

Air Gunner - - Contents -

Neil sets out to gild the lily in part 2 of his Air Arms Pro Sport re­fur­bish­ment

14 In­cluded in the kit there is a hol­low sleeve and a ta­pered plug to help fit the new seal onto the pis­ton. 15 Place the new seal, seal-face down, onto the hol­low sleeve and then en­ter the thin end of the ta­per plug into the seal bore. 16 Tap the ta­per plug down into the seal with a soft mal­let un­til the top face of the plug is flush with the back end of the seal. 17 Place the pis­ton dove­tail ta­per cen­tral over the end of the ta­per plug and then give the pis­ton latch rod a sharp tap down­wards with the soft mal­let. 18 The new seal is now cor­rectly fit­ted onto the pis­ton. 19 With a nee­dle, pick out the orig­i­nal two ‘O’ rings from the end of the com­pres­sion cylin­der and re­place with the two new ones supplied in the kit. 20 Here is the cleaned up pis­ton, with a smear of Moly grease on the out­side of the new seal and on the pis­ton bear­ing sur­faces. Make sure that no grease gets on to the front face of the seal or else diesel­ing will oc­cur. 21 The pis­ton is in­serted in to the com­pres­sion cylin­der and then a smear of Moly grease put on the but­tons and bear­ing of the com­pres­sion cylin­der. 22 In­sert the com­pres­sion cylin­der assem­bly into the rear of the ac­tion, with the cock­ing lever screw hole lined up with the cock­ing slot cut out in the ac­tion. To get the com­pres­sion cylin­der com­pletely down to the bot­tom of to the ac­tion, the anti-bear trap but­ton has to be de­pressed. 23 Put a bit of thread-lock liq­uid on the screw threads of the cock­ing link fix­ing cap head screw

24 Tighten the cap head screw that fixes the cock­ing link to the com­pres­sion cylin­der. 25 Place the main­spring, top hat and main­spring guide assem­bly fully home into the pis­ton.

26 Place the trig­ger block assem­bly into the back of the ac­tion. The more ob­ser­vant of you will no­tice that I have fit­ted an af­ter­mar­ket trig­ger to this unit. This was ob­tained from Rowan Engi­neer­ing. 27 By hold­ing the ri­fle up­right and ex­ert­ing a lit­tle down­ward pres­sure to com­press the main­spring slightly, the re­tain­ing pil­lar nut can be started by hand. 28 Once the pil­lar nut thread has been started by hand, it can be tight­ened with the 11mm AF spanner. 29 Open the cock­ing lever and slide the stock over and re­fit the four coun­ter­sunk screws and the trig­ger guard with its two cap head screws.

Now to put a few pel­lets into my pel­let trap to bed things in a lit­tle and then a ten-shot chrono’ string to see how it is per­form­ing.

That’s a bit bet­ter, we have got an 8 ft/ sec­ond vari­a­tion on muz­zle ve­loc­ity, and a much smoother and qui­eter fir­ing cy­cle.

This ri­fle is now even nicer to shoot, with the re­coil com­ing straight back into the shoul­der, with no dis­cern­able flip.

The scope can now be kept on tar­get when the shot is taken and the pel­let path fol­lowed through the scope.

You couldn’t do this be­fore the V-Mach kit was fit­ted be­cause the tar­get pic­ture was lost be­cause of the slight muz­zle flip that was ini­tially present.

The above re­sults were not ob­tained on the first re­assem­bly. I had to strip it once more af­ter the ini­tial chrono’ string was taken to ad­just the num­ber of spring wash­ers and spac­ers on the main­spring to get the muz­zle en­ergy ex­actly where I wanted it. When do­ing this kind of work you must be pre­pared to do the same as this to get it right.

Any spring-pow­ered air ri­fle, af­ter hav­ing this type of work car­ried out, will in­crease in muz­zle en­ergy by up to 0.5 f.p.e af­ter a few tins of pel­lets have been put through it and the new com­po­nents bed in. There­fore, I am quite happy with these ini­tial read­ings of just over 11 f.p.e, and I am con­fi­dent that the ri­fle will re­main le­gal at un­der the 12 f.p.e. which is an ab­so­lute limit for un­li­cenced air ri­fles in the U.K.

Af­ter putting new springs and pis­ton seals in spring-pow­ered air ri­fles, it is im­per­a­tive that a chrono’ is used so that you know that your ri­fle is, and will re­main, le­gal.

















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