On Mon, 03 Oct 2005 23:19:04 -0500, Don Foreman
wrote:
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?
Its been in my..my experience..that there is indeed some varience as a
result of the same conditions that cause mirage. Which is no more
than heated air defracting light differently. The heated air component
does indeed impart some outside force on the bullets flight, more
noticiable over very long distances. I regularly shoot at 1000 yrds or
more with .30 cals and the thermals a bullet may encounter when
shooting over a long, nonhomogenious distance can add some
complications to ballistics calculation. Plus the air is thinner over
the hotter areas. The shimmer you see is no more than that thermal
air being moved around a bit by faint breezes caused by its own uneven
rises.
I will shoot a tighter 1000 yrd group on a still calm cool day, than I
will on a still calm hot day. Plus of course the mirage effect makes
it difficult to even place the sights on the target..in some
cases..trying to figure out which of the three G mirages IS the real
target can be interesting
Gunner
Confronting Liberals with the facts of reality is very much akin to
clubbing baby seals. It gets boring after a while, but because Liberals are
so stupid it is easy work." Steven M. Barry
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