MAKING A GOOD GUN BETTER
Neil gets to work on a lovely Air Arms Pro Sport to see if he can improve an already fine rifle
A friend of mine with whom I shoot HFT at Kibworth Shooting Grounds, in Leicestershire, bought this beautiful Air Arms Pro Sport in .177 calibre. He had been after one for some time, and eventually bit the bullet and got one. He is so enamoured with it that he told me he wanted it to be the best spring-powered air rifle by far in his collection, and so he asked me to fit a V-Mach kit. Okay, let’s see how it is performing before we start. A ten-shot string was put through my Skan chronograph. This rifle cocked really smoothly and easily and had a very pleasant firing cycle.
I have seen worse spreads from limit in the UK. Right, time for it to come apart.
1 Take out the four hexagon drive countersunk head screws from the fore- end of the stock (two on each side) and then remove the trigger guard by taking out the two hexagon drive screws.
2 With these screws removed, break the cocking lever down.
3 The stock can now be slid forward, clearing the cocking arm and placed somewhere away from the work area for safekeeping. I usually put it straight back into the gun slip that it came in.
4 With an 11mm AF spanner, loosen, but do not remove, the pillar nut that retains the trigger block.
5 Before carrying out this next part of the strip, have a look and make sure that a square section after-market spring has not been fitted. If it has, then the next part must be carried out in a spring compressor because these square section springs have a much greater pre-load length than the standard spring, and when released uncontrolled can shoot out at a tremendous speed and do a lot of damage, especially to your hands. If it is a standard round spring, then hold the barrel of the rifle, stand it upright and exert downward pressure and remove the pillar nut. The mainspring pre-load can then be let down by hand. There is very little pre-load on these rifles, so it is quite safe to do it in this manner without using a spring compressor when a standard spring is fitted.
6 The trigger block, mainspring and guide can now be withdrawn from the rear of the compression cylinder.
7 Take out the hexagon drive cap head screw that holds the cocking lever onto the compression cylinder. This may have thread-lock on it so it could be quite tight.
8 With the cocking lever disengaged, the compression tube and piston assembly can be withdrawn from the rear of the action.
9 Withdraw the piston assembly from the rear of the compression cylinder.
10 If the mainspring ‘top hat’ didn’t come out with the mainspring, as in this case, tap the piston assembly sharply down on to a hard surface to dislodge the top hat. This one was held in place with a lot of grease. If you do not remove this top hat and just fit the new spring on top of it, the spring will become ‘coil-bound’ and the rifle will not cock.
11 Everything that is required is enclosed with the V-Mach kit; a spring with a tight fitting guide and Delrin top hat, power seal, packing washers and spacer, breech ‘O’ rings and lubricants.
12 Now would be the ideal time to clean off all of the grease that used on the initial assembly. Don’t forget to clean out the inside of the compression cylinder to remove any grease residue. I use a couple of sheets of kitchen towel around a suitably sized rod.
13 The original piston seal can be prised from the tapered dovetail location spigot with a thin-handled screwdriver.