The barrel weights are an aftermarket accessory for the lower spec models in the range. A rod screws into the front of the trigger guard extending forward under the air tank. Two sliding weights are provided and can be locked in place with a grub screw, I just use the one, as far forward as it will go.
Like this:- CLICKY
Except.......I made my own
Back to the Gamo trigger now.
I stripped the grips and inner cover off to access the trigger spring. A quick rummage in my bits box and I found a similar size spring (I NEVER throw anything away) that felt like half the effort was needed to stretch it compared with the stock item. Before I fitted it I removed both parts of the sear/trigger and polished them. Both bits are assembled from several stamped laminations and the steel is a bit rough. 5 minutes with a fine needle file, followed by 360 grade silicon carbide tape and oil and then solvol autosol (metal polish) applied with a lolly stick brought them up to a nice shine. A smear of sae30 oil on each part and the two pivot pins and I re-assembled the gun. The result? luuuuuuuuuuuuuverly smooth let off.
And the muzzle flip?......GONE
It was entirely down to me squeezing too hard
This alone seems to have cured the muzzle flip, at least from the quick test I have done so far, more shooting is needed to confirm but if it has cured it then the light weight of this pistol may yet turn out to be an advantage.