On Tue, 04 Oct 2005 01:40:52 GMT, Gunner Asch
wrote:

On Mon, 3 Oct 2005 14:42:30 -0500, "Robert Swinney"
wrote:

Gunner, my question was more about the magnification factor you'd recommend
for .22 RF off the bench. What is your best guess, 20 - 22 X? I want the
opinion of someone that used has some of the high-X scopes for bench
shooting. I fully realize they would be almost useless for hunting, but my
quarry is only a sub-1/4 group at 50 yards.

Ooh..sorry. Yes indeed. Id consider 18x to be the minimum for this
type of work, and 24x the maximum. Even at 50 yrd..with more
magnification..mirage will be a big issue. And of course so will your
heart beat.

Gunner

Is mirage or "shimmer" more of a factor with larger magnification --
or is it just more visible? It would seem to me that it is what it
is -- uncertainty and variability of an optical ray path --
regardless of the magnification used when noting it.

That said, my humble opinion is similar: 20X would be about right.

I don't see much shimmer at 50 yards, even over water at 50X, but it
may be different over hot sand in the desert. I've zero desert
experience.

And now a question: "shimmer" is noise, temporal variance due to
turbulence. But when it is present, there is also usually a vertical
density gradient, which causes "mirage" in the sense of
reflection/refraction that makes a hot surface look wet. The
average density gradient in the air causes refraction. Does this
density gradient also cause "refraction" of the path of a bullet? I
would think so, though the degree would very likely not be the same as
it is for light, but either greater or lesser, and would also
depend strongly on the mass and velocity of the bullet.

Hm. If a bullet is affected by this gradient, would the "shimmer"
(noise, temporal variance) cause a wider dispersion at range
resulting in larger groups?