This is the first post on how to completely disassemble, oil and reblue a Gamo Centre air pistol.
Before continuing to read, you should read this first! It’s important.
My Gamo Centre has been stowed away for quite some time now, and humidity has taken the best over it so to bring it back to life I need to put a few hours of work into it.
As you can see, the entire gun is prety much rusted out. But it can be saved!
What you’ll need to complete this step:
- A workbench
- A confortable seat
- Rubber gloves (one pair)
- One medium screw driver
- One small screw driver
- One 0,6 mm punch or drill bit
- One 0,4 mm punch or drill bit
Before you start make sure the pistol is not loaded. No air in the chamber and no pellet in the receiver. This is basic, but safety should always be your first concern.
The first thing you need to do is to disassemble the grip.
To disassemble the grip the only thing you nees to do is to unscrew the top screw that is located on the grip.
See the orange circle? Be careful because on the other side of the grip there is a small nut (where the screw fits) that is loose and can easily be lost.
You can completely disassemble the grip itself by unscrewing the other screw. I had to do it because they both had rust on them that I needed to fix.
After this simple operation you’ll end up with these parts:
Here you can see the grip separated from the pistol and the grip core (the black part) on the right.
The next step is to separate the trigger assembly from the barrel and compressor.
That is done by unscrewing 3 screws. Two in the front of the trigger assembly (in the picture) and one in the rear, behind the rear sight (sorry didn’t get a photo of that, I’ll update later).
The trigger is mounted on the cast aluminum part and the entire thing comes appart together. Don’t worry, there are no springs or surprises flying around when you disassemble the thing, and it comes appart quite easily.
Here you can see the trigger assembly away from the compressor and barrel.
The next step is to take the lever off the compressor assembly. To do this you’ll need the 0,4mm punch or drill (as I didn’t have a proper punch I just used a drill).
Make sure you leave the cutting bit of the drill upwards, otherwise you’ll scar the metal.
There’s a “pin” holding the lever in place. All you have to do is to take it out. Check the orange circles in the photo above to see its location. Use the drill bit or punch to press it out. Do it in the same direction as the arrow in the photo.
You don’t need to apply a lot of pressure as it is more or less loose (it is kept in place by the cast aluminum piece where the trigger mounts.
To take the lever out all you have to do now is to slide the running piece to the front of the compressor assembly and it’s done.
Be careful not to loose the small plastic piece that is there to avoid direct friction between the lever and the compressor. Another thing you shouldn’t loose is the holding pin as it can be safely reused.
Now it’s time to take out the pellet receiver. The small plastic bit that is attached to the compressor.
To do this you’ll need the thin screw driver, and the screw that holds it in place is located in the front of the compressor, parallel to the barrel.
In the photo below you can see the screw location as well as the small axle with the receiver putted back in it.
As you can see, there are no springs and no bits that can fly out.
This was the easy part. Now lets get to the tricky one. Disassembling the spring. As this pistol is relatively weak, no spring compressor is necessary. You can compress the spring by hand with no problem.
There is only one pin holding the spring in place, and the rear sight assembly is where the spring is fitted inside the compressor.
To disassemble this, all you need to do is to take this pin out and you’re set.
First put the pistol on its side and gently tap on the pin to disloge it a bit. NEVER use a hammer. The grip of the large screw driver is more than enough for the job, and as it is made out of rubber or plastic it will not scar the metal on the gun.
After the pin has moved a few millimitres you can put the 6mm drill bit on it and beat it with the screw driver grip.
This pin is under stress from the interior spring, so you must relieve this pressure. To do this, just support the back of the pistol (the rear sight mount) on the workbench and press the barrel down. It has a tiny gap, maybe half a millimitre, but you’ll feel when it moves. Be very carefull not to support the pressure on the rear sight ajusting wheel. I did that and now I will have to disassemble the entire sight to straigten the wheel screw… To avoind this, use the rim of the workkbench, leaving the wheel off the wood.
Just check the photo below.
After the pin is out, don’t relieve the pressure all at once! Do it slowly until you feel the spring has no pressure in it anymore.
Here is the pin. As you can see, it is not a perfect cylinder, so to take it out (and put back in) all parts need to be perfectly aligned.
The spring will come out attached to the plastic bit that has the rear sight mounted.
There are two more parts you need to take out to completely disassemble the pistol. The compressor piston and the bit that holds the o-ring air seal (this last part I didn’t disassemble because the o-rings are in good condition).
To take out the piston, you need to unscrew the small screw that sits under the compressor just in front of the lever rail.
In red you can see the lever rail and part of the piston (light metal in the centre of the red oval).
Be carefull because this screw looses the back o-ring mount inside the compressor chamber and it’s a real pain to put it back together. Take it out only if it is in bad condition or if you have rust in the receiver lock.
After this you just need to slide the piston back and take it out of the compressor chamber.
To assemble, just follow these steps backwards and it’s done. Pay special attention when inserting the spring lock pin, because of the tension necessary to put it in place, and the propper alignement of the parts.