I bought mine in 1990. It was one of the originally- made in Spain rifles. 23 years later, it still shoots like the best of them. Strong, and reliable, it has a classic look reminiscent of the first old school air rifles from long ago. I've have had great moments in Scouting competitions with this air rifle.
I have had my 3100 for over twenty years now with thousands of rounds shot through it. Great gun overall. The FPS advertised when purchased was 600 fps if I'm not mistaken so the previous post about it shooting 585 would make since. This model to my knowledge never was advertised to shoot in the 800-1000 range. Modern ammo may add some though. Still shooting strong to this day.
I still have one that I purchased new when they were manufactured. (SN 23361) It is still the most accurate air rifle I have. Back when I purchased it, scopes did not work with it because of the unique recoil of the piston air design. I know that is not as much of an issue today. With the hooded site, I could hit something the size of a nickle at around 25 yards. Snails were my favorite targets. My RWS 34 never came close to it in accuracy.(SN 01049048)
I have had this gun for about 10 years. A buddy of mine gave it to me when we were in our late teens cause his dad said he couldnt have it anymore. The outside of the barrel is covered in surface rust and it has been through a garage fire. I put a gamo 4X32 scope on it and have fired THOUSANDS of rounds through it. I can hit a stop sign pole at 35 yards easy. Still has a great kill score on robins at about the same range. Due to the age of the gun at this point I cant give it a 5 because of diminished accuracy and power. But if you have the oppertunity to find one (about 40 bucks on ebay) buy it for a great backyard plinker. Hitting groups of 1/2" at about 10 meters even after all these years and damage done to it. FPS is unknown.