Re: Parrallax with non AO scope
Boltstripper gave the kernal of the answer. It can't be answered exactly. It also shows you need to find out what parallax is and what causes it.
Read this by an Optics Engineer:
http://www.snipercountry.com/Articles/Parallax.asp
when that is committed to MEMORY
read this:
http://www.snipercountry.com/hottips/Parallax.htm
The second reference is Q & A format. No answer is complete but you'll get an idea of the magnitude of the parallax error actual shooters have with real equipment.
Now in light of the explaination by the Optics Engineer, I'll expand on Boltstripper's answer. EVERY DESIGN (and that means EVERY MODEL MADE) of fixed power scope is going to have different parallax charactoristics. And yes, that's EVEN IF both brands/models are parallax corrected to the same distance (say, 100 yards). No one, based on their experience with Model A can tell you what your Model B will do.
It gets more individual (or worse...). Someone with the SAME Make/Model can't tell you what your parallax error at your-- Bourdlay--distance of 500 yards is. First, if your eye is on the scope's axis you should have NO parallax at ANY range. This is not repeatable during a string so we add the extra complication/expense to the design of an adjustment for parallax. It is almost impossible for you to quantify how much your eye is off axis, and for someone else to than match that even if they wanted to try. The average shooter just doesn't own the needed "tools". Second, if you could quantify and communicate this to another, his individual scope (same make/model as yours) is only NOMINALLY set to the same parallax distance. Example: I have three scopes that are all the same make/model. Six months after the first purchase, from the same store I bought, on same day, two more. All seem to be the same. All have a nominal parallax setting of 100 yards according to the manufacturer. In testing, A is 89 yards, B is 91 yards, and C is 110 yards. I'll grant you might suspect my testing of A and B, and that they are really the same (although A ALWAYS tests at a shorter parallax setting than B), and that C really is set for a longer distance. But the point is that NONE of these three SAME MODEL scopes, likely made near the same time, has the same setting on them (nor do they nail the manufacturer's Nominal set distance).
How then, can someone else say what the effect of parallax on YOUR scope will be at 500 yards?