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