Gamo Shadow Teardown and Tune

After tuning the trigger, I decided to tune the action of my Shadow. This was my first magnum springer and I abused it by using both light pellets and adding various combustibles to the chamber. It is now 12 years old and shooting surprisingly strong and consistent. Hard to believe that with the way the spring came out this morning:

Spring had been broken for years
Spring had been broken for years

Don’t spray ether in your compression chamber! I knew better, but it was so much fun at the time. It’s kind of cool seeing and hearing a pellet exit the muzzle at 1600+ fps. The piston seal didn’t have any gouges or burns in spite of all this. The broken end was tangled with the end of the remaining spring and held in place with the tophat.

I’ve gone ahead and ordered a new aftermarket piston seal and spring. I wanted to be able to shoot in the meantime, so I decided to try a spare Chinese B3 spring. The tophat and guide were a much tighter fit than they were with the stock spring. There was a tad more wiggle room between this spring and the piston, but not so much that a bit of heavy grease couldn’t fix.

Getting things ready for installation
Getting things ready for installation

I decided to add a bit more preload to the spring as well as mass to the piston by adding two hardened washers between the tophat and the plastic spacer inside the piston. I lubed everything lightly with Supertech lithium moly grease and reassembled.

How did the tune go? Prior to the tune, it would shoot RWS Superdomes at 836 fps with lots of twang. Now it shoots them at 818 fps with a solid thud, very gas ram like. Cocking is smooth as butter and the shot cycle is to die for. In spite of the weaker, shorter spring, the Shadow only lost a half foot pound of energy. What it gained in smoothness is hard to put a number on.

It’ll be interesting to see how the more efficient seal and powerful spring I ordered will compare to this current tune job. One thing I have learned through all this is that I favor springs over gas rams. With a proper tune, a spring can match the smoothness of a ram. Apparently a stock spring will long outlast a ram as well.

Check out the before and after:

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I've enjoyed shooting and hunting with airguns since my early teen years. For over ten years, I have shared my passion for airguns on this website.

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