I guess I should clarify my post.
Stretchy is a subjective term. I quickly grew tired of requiring two hand grabs on long targets to pull them up. 100# braided Dacron solved that problem. Are the stock strings stretchy compared to a rubber band...no. Are they stretchy compared to Dacron or Spectra...yes.
I owned 50 of the Gamo squirrels for 2 years. They required all the modifications Scott mentioned to keep them operating for a 12fpe rifle. I left my targets out on my course all year. They required constant maintenance to ensure they worked...even after going to the turnbuckle mod.
Contrast that to the 50 Rats on the Run I now own for the past 3 years and the difference is massive. I have done absolutely nothing to the Rats since day one, except replace the string, and they keep on operating flawlessly for 12fpe. They are also made of heavier steel which will last far better with 20fpe guns.
The Rats cost me about 15$ each in bulk. The Gamos were more. I will never bother with a Gamo squirrel again. In fact, I still have a half dozen of them here that I will probably never use again unless there is just a desperate need.
If someone gave me the Gamos...I would just sell them and buy Rats. I would be money ahead in a short period of time, unless I did not have other things to do that can make better use of the time spent modifying and repairing them.
Mike