Author Topic: Modifications Springers and multi pump pneumatics.  (Read 2308 times)

Offline Novagun

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Modifications Springers and multi pump pneumatics.
« on: July 07, 2013, 10:02:10 AM »
Most air rifles are perfectly adequate straight out of the box when brand new. Some are better then others and of course a top line rifle that costs a lot of money will  be better than a budget priced one. No matter how good the rifle is or how much or how little it cost most air rifle shooters want their rifle to do just a little bit better. Perhaps a little bit more accuarate; some want a little more power and some a little less. Some just want it to feel a bit more comfortable or convenient to handle

Let us not differentiate between modification and customisation. Both entail some sort of change. The changes can be very simple and within the capability of most do it yourself enthusiasts and some require special engineering skills that are beyond many people.

The first example is a cheap but perfectly adequate rifle called a Webley Rebel. It is a multi pump pneumatic. That means it has to be pumped up by hand using its internal pump and operated by the front of the stock. It is a quiet gun and has no recoil at all because it does not have a spring/piston mechanism. In .177 calibre it is a modestly powerful rifle capable of taking small game and satisfyingly accurate after a period of shooting to allow all the moving parts to bed in.

The owner of this rifle has extended the stock by adding a wooden spacer, covered with black tape, because the stock was too short for him. He has also added an extension to the pump arm to make it easier to pump and has build up the part near the trigger to form what is known as a hampster. This allows the forehand and arm to tuck in close to the chest while still keeping the rifle properly seated on the shoulder when shooting from a standing position. The cost of these additions was almost nothing and were simple to do. They alter the rifle suit the preferences of the owner and are quickly removable.

The third rifle is a Hatsan model 99. This is a moderately priced rifle made in Turkey. It is a robust rifle and quite powerful in .177 calibre but quite harsh shooting with a strong recoil when used in standard factory trim.

The owner of this rifle has removed the plastic barrel brake and shortened the barrel by 75 millimetres then added a barrel weight on the muzzle.
 The pale coloured piece of timber added to the stock is a cheek rest so that the shooter can get the rifle shouldered in exactly the same position every time. It also helps with the vertical positioning and stability of the rifle when shooting.

What can not be seen from the outside is the 30 grams of steel that has been  drilled out of the piston, the sleeve added inside the piston that stops spring vibration, the 25 mms that has been cut off the spring and the owner made spring guides.

The result of these changes has reduced the muzzle velocity from close to 1000 feet per second down to 800. The rifle is now much smoother to shoot with greatly reduced recoil and better accuracy.

Trigger modifications are probably one of the more common changes made to any air rifle or pistol, and can range from a simple adjustment to the factory item or can extend to dismantling and polishing components or to a complete replacement drop in item such as the "Charlie da Tuna" GRT111 and other models for Gamo rifles and some others. These triggers are available from
The GRT trigger changes the geometry of the trigger, making it smoother and giving it a much more consistent feel and break point. Polishing components will make trigger operation smoother but unless done carefully can change the trigger characterists and not always for the best. DIY trigger modifications need to be tempered with safety considerations.

Other trigger units are available as well, such as the Rowan Engineering Trigger, which is available as a complete unit, or a separate piece to make the factory trigger suit the owners tastes.

The cost of modifications can involved a few dollars for materials and quite a bit of time or sometimes a bit of money for a commercially produced item.

There are also available kits known as Tune Kits from air rifle aftermarket specialists. They usually consist of high quality springs and guides and seals. After installation the air rifle invariably is smoother and more accurate to shoot.

Some home modifications are not something that can be done without access to some fairly expensive tools but others require only a small kit of handtools. The golden rule is that you mess with the manufacturers specifications at your peril but sometimes it works.
« Last Edit: October 31, 2013, 09:03:58 PM by Novagun »