Scope Zero Question?

[whiteleggHW77K]

Finally getting round to fine tuning my zero.

Accuracy was good at 10yrdsish and I though good at 25 yrds (zero).
However when I got round to regularly putting 10 pellets into the same target, I started to see some trends.
At 10 yrds it was hitting consistently 1cm to the right.
And at 25 yrds it was hitting 1/2 inch low and a 1/2 inch to the left.
Figure approximate.

Obviously this cannot be cured by twiddling the knobs....so another solution has to be found.
But what is the likely cause.

Tonight I tried centering the adjustment knobs to start again.
Then slackened of the scope rail clamps and retightend.
Couple of shots at 10yrds an inch left.

Tried slackening off the scope clamps. Then with the rifle supported on two tripods I adjusted the tripods so the reticul was centred on a spot on the target.
When I rotated the scope back and forth, the reticule traced a smile on the target. see mouth left!
Should this happem, or is this a symptom of my problem?
Do I need to shim something, and do I shim inside the rings or between the mounts and the dovetail?

It is an HW77k with two piece four bolt mounts, (so thats 16 bolts in all!)

I'd love to sort this out, 'cause then I can sort out MY technique, and work on getting my zero moved out to 30 then 35 yrds. (The back fence and OH's reluctance to have me firing from the middle of the lounge, prevents a longer zero )

Thanks in advance for any responses.

Pete

[swedey21]

Sounds to me like you scope isnt level with the bore.
how did you mount the scope?
i use a plum line and a spirit level..

[Bales1983]

Im o expert but from what ive read on here in the past your reticle needs adjusting mate,

Shouldnt make a smiley while twisting,

The centre should remain centre all the time.

How to adjust i i do not know but someone here will

Lee

[Murphy]

Lost me!!

[Gwylan]

If the scope isn't exactly optically centred, (and most aren't,) when you rotate the scope in the rings, you will get a "smiley." This doesn't mean there's anything wrong. Do a search on "optically centreing your scope."
If you're only an inch out, I don't see how you can't "twiddle the knobs."
If its a .177, zero at 15 yards, then it should be close at 35, so fine tune at 35 yds. If its a .22, make it 30yds.

Gus

[whiteleggHW77K]

I could just twiddle the knobs...BUT..because it's off to the right at 10yrds and off to the left at 25yrds, I can fix one but not both by zeroing with the turrets.

Optical centering was the way I was thinking of going, Just didn't want to waste my time doing something unnecessary.

With regards to getting the scope level, I have various vertical bits of string and rope round the garden, courtisy of my kids, which tells me when the reticule is vertical....however I haven't quite managed to work out when the rifle is vertical/horizontal, also do I need to worry about the front to back level, and if so do I do this with the scope out....it's a 50mm so the front is taller than the back, so I can't put a level along it.

If anyone has optically centred their scope, I guess by shims (film neg or bits of metal. I am still unsure wether to shim the rings, and risk putting stress on the scope tube, or to shim the dovetails......


Time for bed now.
Hope to pick this up again at 05:00

Pete

[Ideot Savant]

Do a search on here for crossover.

[cnorris517]

Wadoka's right. You have a classic case of crossover.

[Candocad]

Wadoka's right. You have a classic case of crossover.

What, to the darkside ?

All bad jokes apart, what is crossover please ?

Chris.

[Murphy]

All bad jokes apart, what is crossover please ?

Chris.

You know at the weekend when you get the urge to dress in womens.......

Hold on its not what i am thinking of.!!!

[whiteleggHW77K]

Crossover is where the scope is not in line with the barrel.
The result can be mild or severe.
Basically at near targets the pelletes strikes one side of the centreline, and far targets it will strike the other.

Not quite sure why I have developed this as a couple of weeks ago I thought it was spot on!!!

Could be scope shift, as the HW77k has a bit of a kick.....

Any thoughts on what I can screw down through the scope mount into the hole in the top tube of the HW? The holes are there but I don't have any bolts.....

Pete

[ikarma70]

i just put my wtc 3.5-10x40 on my 77k and screwed the horizontal adjustment nearly right the way in(to the left),i thought maybe if i screwed the front mounts top strap right side bolts all the way in and left a large gap on the left ..that might help to compensate?

or is that just 1 silly idea?

[HarryPotter]

Take off the mounts and turn them through 180° so that you clamp them to the rifle from the other side and try again.

Don't worry about elevation, this can sorted later with packers.

Failing that you might need to consider either different mounts / machined mounts to suit your problem (SCR or Keef on here spring to mind) or finally a set of adjustable mounts.

[steveggg]

Pete,

Normally, on 1 of the mounts, there is a grub screw that can be wound out 2 locate into 1 of the holes, or a fixed pin.
Most people use a single mount on springers, as they are more secure if the gun has a kick, usually only tuned guns will take two piece mounts, and as a last resort DAMPA mounts are also used.
Can you tell us what mounts and scope you have.

Steve

[whiteleggHW77K]

The scope is a JSR 6-24x50 from Perry190, the mounts are no-name (I don't know it) two piece double clamp high mounts that perry sent with the scope.. by the look of the lovely website, they look like Accushot ones.

CHECK OUT THE WEBSITE.....NEW SCOPES NEW SCOPES

I think I may have spotted the problem, as I put my rifle away this morning.
I have the scope mounted quite far back, and have put the mounts as far apart as possible....this means that the rear mount was on the end piece of the receiver......the one you unscrew at 20 paces distance incase it launches at your head

On close inspection, it looks like I have quite screwed it back on completely.
So the bevel on that piece is slightly out of allignment with the longer bevel on the rest of the rifle.

I shall move the scope clamp forwards tonight and see if this solves the problem.....if not I shall try tuning one round, then the other, then swap them over etc etc etc...anything to avoid shimming!!!

Pete