I spent some time at the Russian forum and found out that I can get this gun to around 700fps by swapping the mainspring and enlarging the breech.
Here is my mod list:
1. Gamo Mainspring
2. Enlarge the breech to 4mm (the russians say to 3.5mm, but I could get it to 4mm)
Good thing:
I do not have the chronography, but the velocity is incredible and very noticable. With Crossman Hunter Pointed Pellet, it penetrate through the quarter inch wood and still going. It almost make it through the half an inch plywood. I could see the crack on the other side. Accuracy is improved too once you get use to the recoil.
Bad thing:
The Gamo 1000fps mainspring creates so much recoil and noise. I had to wear an earplug for my right ear when shooting it. With the earplug, my right eye would ring after every shoot. I can probably do deaf or hear loss after a while without an earplug.
For those of you who want to do this spring swap, you should know that a DRY FIRE (JUST ONE) will destroy your piston seal with this spring. My first seal is gone because of a dry fire. I'm using the spare one that comes with the gun.
Here are some of the pictures. I am sorry I didn't take a lot of pictures because my hands were so greasy when I did the mod.
Mainspring Swap:
The one on top is the factory mainspring and the bottom one is Gamo mainspring. If you look closely, you'll notice that the Gamo spring is buffer than the factory spring. Interestly, they're the same length so installing it was a piece of cake.
Accuracy with Gamo mainspring at 10 yards:
Notice some of the shoots are bulls eyes and some went through the same hole. I'd say it groups pretty good considering the recoil.
:p :p
That's it folks. This is my very first post on this forum. I hope you enjoy it. :p
Edit: I found a way to avoid damaging the piston seal EVEN IF YOU DRY FIRE IT. I'll post up the pics soon
