Question re zero

[Bad Beagle]

Hawke Panorama 3-9x50, solidly mounted on PCP. Pellet hits centre at 30 yds but one inch to the left at 40 yds. I think the mounts are true is there any other likely culprit ?

your views sought, thanks Steve

[chrisisthe1@lycos.co.uk]

Check the pellet is not spiralling! Been there before

[Rapid7Nick]

What's it like at say 20 yards or a bit closer. Does it shoot off to the opposite side. Maybe the barrel has had a knock, if supported by a barrel band. Have you compared with another scope and mounts to see if the same happens.

[Jonjon79]

Slightly canted scope or rifle?

[Rapid7Nick]

Would swapping the mounts over so dovetail clamp is on the side to see if the problem persists.

[simona]

Is the scope parallax adjustable? I've had scopes where the poi describes a circle as you adjust PA....

[Bad Beagle]

Thanks folks I think I understand all of those... except perhaps the one about spiralling pellets - how do I check for that ??

Ill try the various tests when I get the next opportunity for a plink !

[air-tech]

Thanks folks I think I understand all of those... except perhaps the one about spiralling pellets - how do I check for that ??

Ill try the various tests when I get the next opportunity for a plink !

You are probably canting the rifle towards your face (assuming RH shooter) and have zeroed for 30yd.

Everyone does this to varying degrees (literally).

Only by using a spirit level on the gun or scope will this be exposed, and you will be surprised, what you think is level without doubt will be off, and level will feel odd.

Crosshairs no help as scope may be canted and in any case in the field there is little to align them to.

[angrybear]

Thanks folks I think I understand all of those... except perhaps the one about spiralling pellets - how do I check for that ??

Ill try the various tests when I get the next opportunity for a plink !

Easiest way to check for spiralling is at night with a good shooting torch, against a dark background,
no need for a target just shoot over a field towards a bank/hedge 50yds away, the light should reflect back from the pellet skirt recess allowing you to watch it's flight path,
it's easy with .22/.25 but with .177/.20 you might need to paint the skirt recess with tipex correction fluid to be able to see it.

I think it's more likely to be scope/rifle canted, a good test is to draw a + on the target with a spirit level so the lines are exactly horizontal/vertical with the target mounted & use those lines aligned with the scope reticle cross.

[Sterling]

Another method. (I use).

Spirit level on gun.
Plum-line off tree next to target @ required range. (Ring spanner on long string. Of course it doesn't need to be next to target).
Keeping Rifle level with spirit level, sight scope reticle with plum-line. Tighten scope. Check & check again.
Then send the shots.

If no tree, try variations on a theme.

[Jenny Dipple]

Easiest way to check for spiralling is at night with a good shooting torch, against a dark background,
no need for a target just shoot over a field towards a bank/hedge 50yds away, the light should reflect back from the pellet skirt recess allowing you to watch it's flight path,
it's easy with .22/.25 but with .177/.20 you might need to paint the skirt recess with tipex correction fluid to be able to see it.

I think it's more likely to be scope/rifle canted, a good test is to draw a + on the target with a spirit level so the lines are exactly horizontal/vertical with the target mounted & use those lines aligned with the scope reticle cross.

A good way of seeing if the scope is at fault is shooting the box, you will need a larger target, fire 5 shots at your zero range, then dial scope half a turn right,aim at your original zero fire 5 shots, dial down half a turn and repeat, then dial left half a turn, repeat then up half a turn, repeat, your shots should then be back on your original zero.

[Rapid7Nick]

What rifle have you mounted the scope on.

[Bladerunner too]

What makes you think the mounts are true? have you turned one of the mounts around (only one of them) an then locked them up on the dovetail (next to each other)(without a scope in ) to see if they match up.

[air-tech]

What makes you think the mounts are true? have you turned one of the mounts around (only one of them) an then locked them up on the dovetail (next to each other)(without a scope in ) to see if they match up.

I doubt 1% of guns shoot precisely to where the scope rails are aiming anyway, and whether 1% of scopes themselves actually aim straight with all adjustments at their middle position. That's why they adjust, and why the adjustment available, relatively, is considerable, so even if the mounts were skewed (highly unlikely given how they are manufactured) one would simply adjust to compensate as one adjusts to compensate for everything else.

It really is very likely to be a canting issue. Although zeroing windage makes the barrel and scope line parallel, zeroing elevation does not, it introduces an angle between the barrel and scope line. This so the gun shoots upwards (in relation to the scope line) to compensate for drop due to gravity. So if the gun is held canted, this angle sends the pellet sideways. You can zero to eliminate this sideways, but this will only work at a set distance, the zeroed-for distance. Closer or more distant, the pellet will land to one side or the other, as the angle will come into play.

[air-tech]

I don't have Adobe Flash installed, used to, but have seen this before and it explains things.

http://www.arld1.com/targetplottrajectory3.html