Calibrating an oversized scope on a rifle

[BackyardAirgunner]

Hi everybody

I bought a scope, 6-24x50 from a generic chinese brand, just for fun. I've never had a scope this powerful!

In hindsight, however, I didn't realize how big it was, and my poor old Norica Titan can't break its barrel with the scope attached. Naturally, I got a couple of extra rails to attach it, giving it around 2 inches of extra height. With that, I have enough clearance to break the barrel.

Other than how often I have to tighten every screw on the setup every 15-20 shots, it's not uncomfortable or hard to use, except for one critical detail. For the life of me, I can't seem to calibrate the scope. Now, I am completely ignorant on the topic of scopes, and I learnt how to calibrate thanks to YouTube tutorials, that's about the extent of my knowledge.

Currently, I'm calibrating it at around 13-14 meters. Sadly, I don't have a bigger place to test it at right now, which would be more appropriate for a big scope. Trying it uncalibrated at first, the shots were going almost off my field of view, far to the bottom right. After a lot of adjusting, I ended up with the knobs fully turned up and left. My shots still go bottom right, but not as much anymore.

I realize it was dumb not to take a picture of it, I'll do that later, but say. If my crosshair is centered at the target's bullseye, the shots must go around 2-3 inches low, and 1-1.5 to the right. At least I know there's something about my airgun shooting a bit to the right, because I had to adjust the windage on the iron sights quite a bit to center my shots. However, what could be the issue of the elevation?

Could it be that I'm just shooting at a distance far shorter than the scope is intended for? Or because there's too much spacing between the barrel and the scope for this range? I know it's a generic chinese scope, and I wasn't expecting perfect calibration or for it to hold the zero for long, specially since I'm shooting a springer on top of two rails. But I can't even get it to zero while turning the knobs all the way 

Anyone got any ideas or pointers? At least I can look at the moon very up close with it so that's always a super fun thing to do at night! 

Thanks everyone

[Motorhead]

If scope IS NOT rated for Spring Air Gun use ? being a Powder Burner scope instead ?
It will be short lived having the internals rattle apart fairly quickly.

Barrel break AG's have barrel droop ( as in Receivers dove tail grooves DO NOT run parallel to the barrel bore ) this make all shot go low no mater range.
Angle corrected mount rails or rings is what most do ... Option being up bending barrel slightly to raise POI to an @ 25 yard distance with scope turrets being @ centered.

[BackyardAirgunner]

If scope IS NOT rated for Spring Air Gun use ? being a Powder Burner scope instead ?
It will be short lived having the internals rattle apart fairly quickly.

Barrel break AG's have barrel droop ( as in Receivers dove tail grooves DO NOT run parallel to the barrel bore ) this make all shot go low no mater range.
Angle corrected mount rails or rings is what most do ... Option being up bending barrel slightly to raise POI to an @ 25 yard distance with scope turrets being @ centered.

Oh wow, I had no idea about that with break barrels, even less about angle corrected rails. That's super nice to learn about!

Thank you, I'll rethink about using a scope for this rifle. I mean, I knew it wasn't a good idea in the first place, but learning why is my favorite part. Thanks again!

[chutesnreloads]

Until you have a place to regularly shoot at 40+ meters...get you a 4X fixed power AIRGUN RATED scope. Everything in the previous post still applies.
Tightening the screws every 20 shots will do nothing but frustrate you. Every time you tighten , you'll change zero. Get a lighter AIRGUN RATED scope and suitable mounts