Had a S1k that is now yours, and shot John's (JMG) Gamo "Big Cat" and the only real difference I saw was the bull barrel, which appears to be a thinnish barrel liner with a plastic sleave over it. There were no open sights as I remember, but it came with a scope that could be adjusted by dropping it on a rock. Same stock, same action, same, same, same except for the barrel and the barrel pivot that also seamed to be covered in plastic...like a Cadet or Delta...whatever you want to call it. This is all just from memory, I don't have either gun in front of me at the moment.
Dan