Scope won't adjust any further

[RandyRay41]

Ok I know it's cheap but I have a gamo big cat. Using the scope that came with it I have the scope adjustment turned all the way to the left or maybe 1 or 2 clicks till no more. Just wondering if the scope is fubar or is the barrel bent? Had the gun less than a month. Was shooting fine took it camping with me where the gun rode in a boat for about 20 minutes. When I tried to shoot it later it wouldn't hit broad side of a barn.

I have it sighted in now but no further room for adjustment. It shoots nice groups and took 5 squirrels out of national forest from some real high oaks this morning Just bothers me about the scope adjustment.

Any thoughts on how I can check if barrel is aligned or the scope is messes up?

 

[ChaoSS]

Check your rings. One piece or two piece? Weaver or Dovetail? If the rings are out of alignment, you could be having this issue.

Also check the pivot on the barrel. Is it loose?

 

[RandyRay41]

The rings are 2 piece dovetail. They are the ones that came with rifle. All the screws are tight and There's no wobble in barrel. It's sighted in now. Shoots straight. Just now way to adjust further left if it needed to be.

 

[ChaoSS]

The rifle i have that has a dovetail mount has to be done carefully. The screws being tight doesn't mean that they are aligned properly. Try loosening them up a bit, adjusting the scope to the left a bit, and tightening it back up.

 

[RussB]

The scope attaches to the receiver, and the barrel pivots in that receiver as well. It takes some precision machining and fitting to keep the barrel lock-up consistent.

Next is the low end scope. Air guns put a whoopin' on scopes, often breaking the adjustment mechanisms and/or jarring the lenses loose.

Then there are the scope rings themselves. It takes a well cut dovetail that's properly aligned with the bore's axis along with sturdy rings to keep it all where you want it


Make sure the action is tight in the stocks, and also check/adjust the barrel pivot. It is very common for scopes to move in the rings, or the rings/scope assembly to move on the receiver.

 

[Chevota]

It probably has barrel droop which means you've cranked the elevation screw in to compensate, correct? The further one knob is adjusted the less the other know can be adjusted. Say you center the adj knobs so you can go 3 turns in any direction, then you crank the elevation down 2 turns from center to compensate for the barrel droop. Now your windage will only have maybe 1 turn in either direction.
To fix this you can use shims of sheetmetal under the scope, maybe alum from soda cans. With a few layers of shims you can set your scope to line up with the barrel which means your elevation is closer to center which brings back your windage adjustment. You can also put the shims more toward the side so it compensates for your windage error as well.
Many scopes work better with one or both screws turned in more so you might leave the elevation turned in and just shim the side enough so you can get on target.
The reason I say "work better" is because the shock of the gun when firing can upset the adjustment because it's held in position by a little spring, but the further either or both screws are turned in the more pressure they put on the return spring which helps keep it from moving. Look down the front lens with a flashlight and you can see how the W/E screws and the leaf spring interact and it'll make sense.
So how much pressure you need on the spring to hold it on target depends on how abusive your gun is and how strong the spring in the scope is.
Like parallax error, this spring problem can cause mysterious accuracy problems that make people think it's the gun.