Scope Zero Question?

[Gwylan]

Pete... in your first post, you implied that your scope was zeroed at 25yards, then you said it was shooting right at 25 yards, so your zero has shifted in some way. Have you got a rifle like the S400, where a knock on the muzzle can shift barrell alignment?

Gus

[whiteleggHW77K]

Good point.
Yes it has been knocked in the past, but I thought I had corrected that.

When I said previously it was zero'd at 25yrds.....I thought it was.
Being a springer, it isn't possible to clamp it in the workmate and force it to stay still, so the quality of my zeroing is somewhat dependant on the quality and consistency of my hold.

What I mean by zero is 'acceptable' accuracy.
Only now when I'm sending alot more pellets towards the target am I seeing trends that show me something is wrong, it would appear that before this had been hidden by my wobbles!

Pete

[Dave E]

I can't see that crossover could give you such a large error.
With the figures you have given I assume the horizontal zero is at 20 yds.
This indicates that the scope and barrel are out of line by about 2cm at the muzzle.
Assuming your scope centre is about 44mm above the barrel you could get that error by canting the gun by about 23 degrees of the vertical or the equivalent combination of cant and scope not set truely vertical with the barrel.

[whiteleggHW77K]

Right,

Did a bit more work on this, this evening.
Took the stock of and screwed the end of the receiver in a little bit more to make the dovetails line up porperly.

Seems a bit better.

With a few bits of packing to bring the front mount up a bit.
I have got it spot on at 25yrds.
But at 11yrds (my other zero according to chairgun) it is approx 5mm to 1cm to the right.

Now for hunting, provided this remains constant, I can live with.
Once I loose the cover of the bushes and wind and other factors come into play, a 5mm tollerance narrowing to zero is minor.

But it is still frustrating

I guess I need to shift the back of the scope to the right very slightly.
Will try slackening the right of the scope mount and tightening the left to see if it has an effect.

I will report back.

Pete

[whiteleggHW77K]

To Dave E

I will check the 'verticalness' of my set up.

I do have a bubble on the back of the stock, so I attemot to have a consistent cant or lack of it!

I can work out how to get the scope level, but how do I know that the rifle is level as well! where do I put a level to check that?

Pete

[Dave E]

pete,

re read this thread and getting confused.

Clamp the gun and mount a spirit level accross the dovetails. Get the gun level by shimming the clamp feet. Now look through the scope at a plumb line and rotate the scope until the vertical is true.
Not sure about this next bit 'cause I've never tried it! ; if the plumb line is in front of a mirror you could see if it cuts through the centre of the barrel and scope when looked at from behind scope. You'd have to get the distance right by trial and error to get a reasonable view. This might show if your barrel is out of line.

After you're happy with this, hold the gun to your shoulder as if shooting and see if it lines up with the plumb line or if you are holding it on the cant.

I think you need to do one thing at a time.