Wild elevation shots.

I have a Gamo Whisper Silent Cat I bought in 2014. I shot regularly in my backyard for 2 years, but then changed jobs and couldn't shoot anymore. Four years later, I change jobs again and am back to shooting 2 - 3 times per week. At first the factory supplied scope was way off. I got windage zeroed and it is fine. Elevation hits anywhere from 12" high to 18" low, and it will not adjust at all. The only other scope I have is a Tapsco firearm scope. I put it on and it constantly shoots 6 - 18" low. Again windage is fine. I went back to the Gamo scope and still have that wild 24" plus variation. 2 or 3 shots out of every 10 to 15 hit the bull. I am perplexed and frustrated. Could it be the gun instead of the sight? What would cause this? I have tried several pellets of Crossman and Gamo and they all do the same. HELP!
 
Buy a spring gun rated scope such as a Vortex Crossfire2 4-12x40ao BDC from OPTICS Planet $189-10% off in house coupon and 59.95 BKL 1 Piece .007 DROOP COMPENSATED MOUNTS and be done the first time. The .007 BKL drooper mounts will correct your shots stratght on target.

The scopes and mounts that come free with the SPRING or gas ram guns are total rubbish unless you buy Weihrauch from AoA. Of course you are gonna have crazy wild shots with those included scopes. Some may have good luck however not most.
 
The gun shoots perfectly using the open sights. I bought another pair of rings although they are firearm rings; not airgun, and yes they slide backwards. I have tried every combination using the 2 scopes and 2 pairs of rings, and I am still hitting from 8" - 10" high to 10" - 18" low. I put up a 4 x 4 piece of plywood at 15 yards. With targets in the center, I end up with an almost straight line of holes from top to bottom of the plywood. As I said, left to right windage zeroed in fine. I have mounted and remounted both scopes several times, leveling them as best as I can. I have oiled the seal and cleaned the barrel and don't know what else to do. I emailed Gamo about it and they said I should send it in for repair. But if it shoots fine with open sights, what are they going to do to it? They want $40 for the repair and $15 for return shipping. If it cost me $15 to send it to them, that's $70. I'm afraid I'll send it in and they will say there is nothing wrong. If I do send it, would I send both scopes along? They might work on their scope that came with the gun, but they certainly won't work on the Tasco firearm scope. I don't have the budget to buy as Yo recommended, but I have bought a new spring rated scope and new rings with slide stop. They should be arriving in a couple of days. I am hoping that will solve my problem, but if it doesn't, I don't know where to go next. Has anyone ever experienced anything like this before?


 
Assuming the rear open sight is mounted on the barrel or receiver block (seems most are), then it might be lockup inconsistency. The open sights would follow the barrel but a receiver mounted scope would not. I did have this issue on a Hatsan 125 several years ago. I did some work to increase lockup pressure and improved accuracy dramatically. Still have the rifle today. It takes a good slap to break the action and a good snap to close it but I can live with that for the improved consistency.
 
Assuming the rear open sight is mounted on the barrel or receiver block (seems most are), then it might be lockup inconsistency. The open sights would follow the barrel but a receiver mounted scope would not. I did have this issue on a Hatsan 125 several years ago. I did some work to increase lockup pressure and improved accuracy dramatically. Still have the rifle today. It takes a good slap to break the action and a good snap to close it but I can live with that for the improved consistency.

I'm with you.