scope "walking"

[DevineIntervention]

I have a Ruger Mini-30, 7.62x39. I finally got a nice scope for it and installed it on a used m-14 style scope mount built for the Mini-14/30. The scope is a "Leapers UTG 3-12x44 Accushot 30mm Compact IE scope". Zeroed it in at 20 yds using bore sighter and iron sights. First shot just missed the bull, hit less than 1/4 inch low and less than 1/4 inch left. Next round hit 1 1/2 inch below that, next hit 1 1/2 inch below the last, and continued for a total of 5 rounds 1st almost perfect bull, eash subsequent shot 1 1/2 inch below the last. I set up the iron sights and boresight again and found that the cross hairs of the scope were now off the page above the bullseye. My shells eject with no dents or scratches and almost perfectly horizontal. I already ordered lower scope rings, and a new better built scope rail.
Does anyone know what specifically happening to cause the crosshairs to jump 1 1/2 inch each shot at only 20 yds?!

[603Country]

Could be that you have a bad scope. It happens. If you have another one you can swap out, so try that.

I had an expensive scope die gradually on the gun. Groups got worse and worse, but I was very slow to consider that the scope was the problem. It was new, and I'd never had a brand new scope die. I can't say that anymore.

[George Hill]

Before you check the scope - check the mounts. Rings and Bases.
This means taking the scope off, Loctiting the bases and remounting from the ground up.

If it's still playing around, then it's the scope its self and your options are to 1. Send it to the Optics Manufacturer for Warranty if it has any.
2. Replace the scope.

[Roughedge]

If your scope and mounts are tight try cleaning the barrel real good. What ammo are you using? That can make a big difference. The mini-30 is'nt know to be the most accurate gun but it should do better than that.

[James K]

Scope adjustments are made by a screw moving the reticle against a spring. If that mechanism is loose, it can cause the crosshairs to move. Sometimes, you can detect looseness simply by moving the adjusting knob and feeling if it moves too easily or has no "clicks" at all.

Jim

[Daggitt]

In my humble opinion I would not put Loctite on it or at least not yet. If the scope is shot you are going to be taking it off again real soon. You might regret the Loctite.

[jmr40]

Leapers scopes are not known to be of high quality. Semi-autos are harder on scopes than other types. The Ruger Ranch rifles have a good scope mounting system. The standard rifles do not. Ruger mini 14/30's are not known for good accuracy. I'd say a combination of a poor quality scope mounted on a rifle not designed for scope use along with other factors.

I set up the iron sights and boresight again and found that the cross hairs of the scope were now off the page above the bullseye.

With scopes mounted very high above the bore this is not uncommon, especially when trying to zero at close range.

If it were my gun, I'd just use the irons, or trade for a rifle designed to use optics. Mounting optics on this rifle is just not going to be worth the effort.