First a brief reflection of how I and those I know/work with test and why most don't even know their scopes aren't working.
Most mount a scope, bore sight, fire 1-3 rounds, adjust, fire 1-3 rounds and if the bullets are somewhere near their "zero" (usually 1-3 inches high at 100 yds), then they say the are done. If the scope seemed like it adjusted the bullets close to the desired amount they state that the scope works fine. Really the only thing they care about is staring at and bragging about the "glass".
There are several problems with this.
1) The most important is that just about every name scope has glass that is more than sufficient to see with and kill under just about any legal light. "Glass" is just about last on the list of importance for almost any use. Doesn't matter if it's long range shooting or hunting in the timber with a lever gun. You are far more likely to miss or wound an animal because the sighting device lost zero or adjusted incorrectly than you are because you couldn't see it to shoot.
2) 3 round "groups" are completely and totally insufficient to determine where any one shot will land. There is no- "hunting rifle", "1st shot from cold bore", "only the first shot matters"- nonsense. ALL guns fire in a cone. This is a fact. The purpose if zeroing is to move the center of the cone to point of aim (POA). It takes a certain number of shots to adequately determine where the center of the cone is. If you have a rifle that generally produces 3 shot "groups" of around 1 MOA, than you really have a gun that is somewhere between 1.5 and 2 MOA for the cone. This is important to understand as those three shots are almost meaningless and has a high likely good of being farthest from the center, rather than closest (there is more to it than that). That means that when you think you are zeroed, you can be almost 2 MOA off from actual ZERO. This alone should make it fairly obvious that doing the above will never allow one to see point of impact (POI) shifts of .5 to 1 MOA. Let alone knowing what size target we can hit, or if the scope is adjusting correctly.
3) Adjustments of a few MOA shows nothing of a scopes correct functioning. Lots of scopes have dead spots, shifts, under adjustments, over adjustments, flat spots, backlash, failure to return to zero, etc., anywhere throughout the adjustment range. Only tall target tests, with frequent POI measurement will show this. Adjustments of 30 plus MOA/10 mils with POI measuerd at least every 4-5 MOA/1 mil is needed. Now there will be plenty claiming that they don't shoot far enough for it to matter, however that's not the point. Any of the above conditions point to mechanical problems and a high likelihood of future problems that are much more severe.
Scopes don't get "better" with use. Any scope that exhibits the above issues is broke and will only get worse. Again most will say that none of that matters for none turret twisters... that is flat out wrong. For instance- a regular hunting scope say even a fixed 4x that will never be dialed, has dead spots, shifts and backlash. Doesn't matter once the scope is zeroed, right? Wrong. Those conditions are a sign of a faulty erector system, an erector system that is designed to be stable and in correct function in order to maintain zero. All else being equal that scope will have a measurably shorter life and a way higher probability of failing at any time.
This is a scope that was never dialed. There are plenty of really good three shot groups in both targets, and they even overlap somewhat. Firing just 3 rounds may have not shown the shift. Or it could have been attributed to any number of other factors.
Here is the exact same scope a year later after being totally remounted and a trip to Afghanistan with no abuse other than normal use, being zeroed before a major match.
Exactly one day later after going down in the middle of a LR stage
Top " group" was shot first, followed by the bottom with no adjustments made. Notice the two rounds right of the dot were fired first, then it shifted and the third is the one on the edge of the cardboard.
This can and does happen to hunting scopes ALL THE TIME. But most don't see it because of several reason i get to below and those above.
4) "Zeroing". The only way to have a true zero- that is the center of the cone overlapping the point of aim..... Is to have the center of the cone overlapping the point of aim. You do not have a zero if your gun is sighted in 2 inches high at 100. Or you do, but you have no knowledge of where that zero actually is. You may think it's close, and it may be to some uncertain point down range, but unless you fire enough shots to determine POI at THAT SPECIFIC range and have the POI match exactly the POA, you are guessing that it is zeroed. You do not know.
This-
And this-
Is NOT zeroed.
This-
(Sorry about the finger. Smack talk knows no bounds... grin).
And this-
(POA was the tip of the diamond)
Is zeroed. Both are 10 round groups and both are centered over the point of aim to the mechanical limit of the adjustments. Any zero shift will be immediately apparent.
5) Constant tinkering and changing ammo. It is impossible to determine stability in the scope if you change ammo, lots, or makes. Most are constantly tinkering with "loads" and therefor can have no idea whether the zero shifted.
How the zeroing process should go-
1) Choose scopes based on mechanical function first. Reliability and durability mean more than every other attribute.
2) Mount properly with a ring and base system proven to be extremely stable and durable.
3) Zero with 10 round groups at a minimum, insuring that you have 100% point of aim, point of impact.
4) Conduct a tall target test to show any erector flaws.
5) Ensure that what the ammo that was initially used to zero is used to check zero every single time it is shot. Same make, same brand, same lot. If hand loads are used then have enough left over to check long term.
5) Give absolutely no excuse for zero shifts, "fliers", or any hiccups with the scope. Any shift in POI/POA is a failure, even the first time, and WILL HAPPEN again.
Bottom line is that of my bullets aren't going to crosshair intersection, I do not fire enough rounds to determine both the center of the group and mechanically what size target those rounds will hit, and I do not test mechanical function, I have no idea if the scope is working, no clue or advance knowledge of potential problems, no idea whether it will even hold zero, and no idea whether a missed shot or wound was me or my equipment failing.
I have had a Swarovski hunting scope since 2008, and it's a fine optic sight. Oh, and my mistake: Schott is a separate company from Zeiss. Zeiss makes glass for themselves and others, Schott is just a glass company.
