Zero shift

Utectok

Well-Known Member
Ok shot a deer the other day thought that’s not quite where I was aiming. Toddled off for a zero check (checked mount were tight first) and it was about three clicks right and two clicks high. No biggie fixed and checked.
How often do you lot zero check and how much is your rifle off, it is? Just curious I’ve just put on a new set of mounts and a scope so I really hoped it would never need a new zero lol!
 
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caberslash

Well-Known Member
You do realise that by tightening the mounts you could have moved the scope and shifted zero?

This is why all my rifles use rails or integrated dovetails, much less likely to move when epoxy bedded and used properly with good (Spuhr Hunting) mounts.
 

Utectok

Well-Known Member
You do realise that by tightening the mounts you could have moved the scope and shifted zero?

This is why all my rifles use rails or integrated dovetails, much less likely to move when epoxy bedded and used properly with good (Spuhr Hunting) mounts.
Funnily enough it was a rail bedded with the loctite 638 and spuhr hunting mounts 😉
 

Utectok

Well-Known Member
Mind blown... what was the scope?

Did you use a quality (Wiha or Wera) torque wrench?
Its a Schmidt and bender ultra bright I confess I didn’t use a torque wrench perhaps I should have but I’m really surprised the zero shifted. Maybe this warm Scottish weather tweaked the load a bit?
 

Koenig

Well-Known Member
Could be a number of things. I was pulling high left recently-couldn’t work out why. As soon as somebody watched me he picked it up straight away : I was gripping the forend too tight and it was throwing me off. Have you changed any aspect of how you shoot or your kit setup lately? Chances are that’s worth looking at. Any oil in the barrel? Seen that send shots off before even at normal UK deer ranges. It sounds like you have a good mount set up, but it’s always worth checking it over for tightness, as I found to my cost with a set of Optilocks that shook themselves loose just before my DSC1 shoot years ago! My language was unrepeatable🤣.
 

Sonicdmb73

Well-Known Member
Its a Schmidt and bender ultra bright I confess I didn’t use a torque wrench perhaps I should have but I’m really surprised the zero shifted. Maybe this warm Scottish weather tweaked the load a bit?
Temperature change. Slightly different wind. Head in a slightly different place. The list goes on.
My former boss and stalking mentor always used the 1” high method (don’t get me started on that). But with his rifle my groups were always on the POA.
 

Heym SR20

Well-Known Member
Zero can and does change. Well no it doesn’t but you change. I learnt this early shooting .22 target rifles. I used the same BSA Martini and every session you would move it a couple of clicks each way before shooting a score.

I make sure everything is nice and tight and then zero the rifle. I do check it from time to time, but most of the time I never bother adjusting anything. Sometimes its slighty off, but it is well within the probability of a group. Most good rifles shoot most ammo into a 1 to 2” sized group at 100. Some will do better. That’s not a 3 shot but 10 plus shots. So doing a check shot or two doesn’t really tell you much - they might be centre of group, or might be the edge.

What I would do is to have the same target and shot one round at the target over several days, in all sorts of weather and from different positions - this will teach you a lot about how your rifle shoots from a cold barrel. In a hunting rifle 90% plus of shots will be a cold barrel, or for many of us a cold, clean barrel. How a barrel shots warm is pretty immaterial.

If your group is consistently off then by all means adjust by a click or two.
 

Utectok

Well-Known Member
So after scratching my head a bit I remembered taking the forend off and seeing a very small mark in the barrel right at the base which was obviously rubbing the forend. I shaved a bit of the forend to get good clearance and thought right at the base of the barrel it won’t affect resonance. Clearly it did I pretty certain the removal of the obstruction to free barrel movement affected point of aim a very little bit. Anyway it’s shooting 0.3moa on the bull now which is slightly better than normal 0.5moa let’s see if it holds.
 
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