Originally Posted by
JSantoro
This is sorta in the realm of "what it means," such as what it actually means when an optic is tagged as "parallax-free." It's absolutely impossible to make anything in which light passes through glass bo be parallax-free (SCIENCE!). In the end, it basically means that the manufacturer has made it as parallax-free as the physical laws of the universe allow it to be. Like with anything measurable, there's a low end (failure), the desired goal, (threshold) and a high end (objective).
With mounts, what the phrase "return-to-zero" really means is that, when you remove the mount for whatever reason, so long as you remain consistent in your remount procedure (same gun, same place on the gun, same method each time), you should see no more than a .5MOA shift.
If you consistently see greater deviation than that, that's a FAIL.
If you consistently see it meeting .5MOA deviation, your mount(s) has achieved the THRESHOLD. It's good, solid, within desirable tolerances.
If you see it consistently showing devaition less than .5MOA or even NO deviation, you are a bastard and I hate you. Not really, your mount is simply achieving the OBJECTIVE.
Everything is subjective to how drunk the little old lady in the factory is that day, what the QC practices of the vendor in question are, sunspots, and the unanticipated appearance of the Spanish Inquisition. There are vendors that do a good job of of keeping those instances to a minimum. After that, you have intangibles like the differeing intensity levels of Silly-Straw Chromosomes that any given user might have....there are always unaccountable, indefinable variables.
This is why ADM, LR, BoBro, and a few others are heartily recommended. It's not fanboy-ism, it's the fact that there is a measurable incidence of their equipment (with all other things being considered equal) consistently meeting and usually exceeding threshold.
EDIT: For clarity, in most instances, all one'll see on a performance spec is threshold/objective, so anything not meeting threshold is considered to have failed.
