Reassembly of the S20 is not easy. Rather than use screws like any normal airgun (with the non exception of the equally abnormal Tempest and Hurricane), the pistol is largely press fit together. So although it needed cleaning, if it worked fine I would never take one apart again.
Piston head is rough ground.
Spring end is pretty rough
Spring guide is downright crude.
Cocking arm has been gnawed by rats.
After much time smoothing and polishing. Not perfect but much smoother.
I had to use slave pins extensively to hold pieces in alignment so I could tap the pins home.
This was very important with the breech assembly, as it has to be hammered back into the slot with a dead blow soft face hammer.
A small slave pin holds the trigger spring in place. Unfortunately, shortly after this I ended up losing my grip and the trigger spring escaped somewhere in the shop, without making a telltale noise upon landing.
So I wound a new trigger spring. Dead simple.
Although I had to make two, the first (R) being somewhat too small.
Back in place.
I forgot about the plate washer that goes inside the grips
It goes here.
So the pistol is back together, lubed and adjusted. It feels better and seems to have a nicer action. I will say that the above took many hours of work, so again, I would never take one apart if I didn’t absolutely have to.