If A Scope " Loses Its Zero ", How Does That Manifest Itself?

[entropy]

"Losing Zero" is a manifestation itself, of one of many different possible problems with a scope.

 

[Turkeytider]

Many thanks all. REALLY appreciate everyone`s input into this thread. Good news!! Verified original zeroes on a couple of loads ( 69 and 75 grain ), sub-MOA groups at 100 yards. 500 yard range, back to normal hit frequencies. I haven`t the foggiest idea what happened yesterday, although in retrospect I do recall some shifting breezes that maybe I didn`t account for(?). It is a .223 after all! Anyway, scope ain`t broke!

 

[film495]

Many thanks all. REALLY appreciate everyone`s input into this thread. Good news!! Verified original zeroes on a couple of loads ( 69 and 75 grain ), sub-MOA groups at 100 yards. 500 yard range, back to normal hit frequencies. I haven`t the foggiest idea what happened yesterday, although in retrospect I do recall some shifting breezes that maybe I didn`t account for(?). It is a .223 after all! Anyway, scope ain`t broke!

right. I've never shot out to 500 yards, but - when missing, shooting a closer target is all we do and go from there.

 

[Walkalong]

I do recall some shifting breezes that

I almost asked about conditions, they’ll make you scratch your head sometimes. I always shake my head when someone stoically and firmly says the wind won’t affect caliber xyz at x yardage.

 

[Turkeytider]

I almost asked about conditions, they’ll make you scratch your head sometimes. I always shake my head when someone stoically and firmly says the wind won’t affect caliber xyz at x yardage.

I don`t know. I dd notice mirage through the scope that was vertical, so I really wasn`t paying attention to the wind. I think 500 yards is plenty of opportunity for wind to impact a .223 round.

 

[doubleh]

I have only had two that lost zero They went from being on target to not even able to see where my shots were hitting and wouldn't adjust at all. If I had zero change just a little with the same ammo it has always been a base loosening or a stock warping but usually a loose base. That is why I always put fingernail polish on base screws now.

 

[Walkalong]

I think 500 yards is plenty of opportunity for wind to impact a .223 round.

Absolutely.

 

[BushMaster-15]

I don`t know. I dd notice mirage through the scope that was vertical, so I really wasn`t paying attention to the wind. I think 500 yards is plenty of opportunity for wind to impact a .223 round.

The ONLY way to know for sure is ,RE-ZERO at your normal yardage and print paper . I've never had it happen but a friend had a reticle or internal part drop in a scope once .

You can damage your scope and affect your zero if any part of your scope touches any part of your rifle. Years ago Zeiss showed a super slow motion video with a free floating barrel ,which actually hit the scopes objective bell it was mounted way too close .

Over tightening a scopes tube can most certainly damage ANY scope regardless of quality . Why the vast number of shooters I know LAP RINGS for that PERFECT fit . Last but not least recoil can eventually whack a scope . I did it on a cheap Tasco with .22 Rimfire ,granted took 30 years but it did happen .

 

[ms6852]

If this has happened suddenly there are a number of issues that could affect your point of aim. Most have been addressed and others have not. Hypothetically speaking since your skills are rudimentary you are shooting at very long distance for someone with your skill set. Also let us assume that your action and scope are not loose, then there is the question of bullet weight. Has this changed? At the distances you are shooting a change in bullet weight from a lighter bullet to a heavier bullet will drop inches enough to miss the target and vice versa. If you have not checked the velocity of your factory ammo with a chronograph this should be in order. You should not expect the same velocity out of your rifle from what is posted on the box as their barrel used at the factory will be different from yours. Your barrel could be shorter or longer.

Second thing to take into consideration is the temperature outside when you were shooting. Cold air is denser than warm air and provides more drag on the bullet causing to loose velocity a lot faster and at 500 yards . Now that temperature changes are occurring a 20º temperature drop could equate to about a 2.5 to 3 inch drop or about 1/2 moa at 500 yards.

Another thing to consider is have you cleaned your bore and barrel of your rifle, do you have a copper or leading issue. If everything checks out get back to basics check your sight picture is it the same, is your cheek weld the same, is your trigger control the same are you squeezing or jerking. Best way to check to see if you are jerking the trigger is to do dry firing exercises. While you are holding the rifle (UNLOADED) as you are going to shoot it have some one place a dime at the end of the barrel and squeeze trigger as you normally do. If the dime falls, you did not squeeze the trigger you jerked it. Do this daily until you can do it repeatedly 10 times without the dime falling, that is trigger control.

Last thing I can think of is your breathing are you shooting while breathing, are you holding your breath while shooting, if it is taking you too long to get your sight picture and you are holding your breath you may have a tendency to hurry your shot because you want to breathe. I prefer to squeeze the trigger at the moment that I let my breath out slowly while maintaining my sight picture and the moment I stop exhaling I shoot.