From: bartb@hpfcla.fc.hp.com (Bart Bobbitt)
Newsgroups: rec.guns
Subject: Re: best rifle for 1000 yards
Date: 17 May 1994 09:47:15 -0400

Larry M. Jordan (jordan@aero.org) wrote:

: I own a Ruger M77 MkII in .308 with a sporter-weight (correct term?)
: 22" barrel.  It shoots very well, as far as I can tell (quarter-size groups
: at 100 yards.)  With this shorter barrel, what is the maximum 'effective'
: range?  Is a 1000 yards out of the question?

That depends on what size target you want to hit, or the greatest distance
you want to miss your point of aim.

It has been my experience (and many others, too), that there's about a 1:5
ratio between 100-yard and 1000-yard performance for accuracy.  In other
words, to shoot 1 MOA at 1000 yards (10-inch groups), the rifle/ammo/sight
system must shoot 0.2 MOA at 100 yards (2/10ths-inch groups).  It is a
good rule of thumb that one can predict fairly closely what their 1000-yard
groups will be by multiplying the 100-yard MOA size by 5.

Traditional benchresters have about a 1:2 ratio between 100 and 300 yards.
Their 300-yard groups are about 2 times in MOA larger than at 100 yards.
1/10th-in. groups at 100 yards translates to 6/10ths-in. groups at 300.

Smallbore shooters have a similar situation.  At 50 yards, their .22 rimfire
rifle/ammo/sight system can produce 1/10th-in. groups, or .2 MOA.  At 100
yards, groups about 6/10ths-in. are produced; .6 MOA.  That's a 1:3 ratio.

The two big factors contributing to groups not increasing linear with range
are velocity spread and unbalanced bullets.  Every bullet fired has some
amount of unbalance and they don't all leave at the same speed.

An excellent example of this is what ones .308 Win. does with Sierra's
168-gr. HPMK bullet.  Those bullets are tested indoors at 100 yards for
accuracy and typically group between 1/10th and 2/10ths of an inch from
machine rested test barrels; all they are doing is measuring the uniformity
of the bullet.  To shoot that well, those bullets are very well balanced
leaving the test barrel.  If a rifle shoots 'em into no better than 7/10ths
of an inch at 100 yards, something is unbalancing them too much or pointing
the muzzle at different places relative to the line-of-sight for each shot.
If the barreled action is proper and well bedded, the error is almost 100%
caused by unbalanced bullets and/or velocity spread.

BB

From: bartbob@aol.com (Bartbob)
Newsgroups: rec.guns
Subject: Re: "Quigley down under"
Date: 14 Jan 1996 17:30:21 -0500

It's interesting to note that none of the tiny groups mentioned
in responses equate in any way with what's shot at Camp
Perry.  Those quotes are benchrest groups.  Camp Perry
matches at 1000 yards are shot from the prone position
without rests of any kind.

The 10 ring on 1000-yard targets is 20 inches in diameter.  It's
rare if anybody keeps all their record shots at Perry inside the
10 ring.  Usually one or two will leak out and go in the 9 ring.
The record for the 1000-yard match where scopes are allowed is
200-15X; 15 shots inside the 10-inch diameter 10 ring; the others
inside the 20-inch 10 ring.

And remember that 1000-yard benchrest groups that set records
are the smallest fired, not the average.  And they only fire 10 shots
for record, not 20 like prone shooters do.

Rifle accuracy with either is typically in the 7 to 12 inch range at
1000 yards.  It depends on how one corrects for wind, holds the rifle
still, and lets the shot off well that determines the winner either by
points or smallest group.  At 1000-yard benchrest matches, the
typical group size of each relay's winner, and the match winner, is
8 to 11 inches.

Don't forget that Skip Talbots few-inch group with a 50 BMG followed a
24-inch one.  Rifles don't shoot their smallest groups all the time, just
rarely.


Regarding "Quigley's" rifle, no rifle made in the era depicted in the
movie
would shoot that well.  The best 44 and 45 caliber match rifles used at
1000 yards in the late 1800s would put 20 shots in about 30 inches.  We
have come a long way since then.

BB

From: dmc@io.org (Daniel Chisholm)
Newsgroups: rec.guns
Subject: Re: Gun magazine shot groups
Date: 3 Dec 1995 18:42:38 -0500
Lines: 80

In article <49qtuk$7k@newsbf02.news.aol.com>,
ZCarter530 <zcarter530@aol.com> wrote:

#OK, here's four reasons why I think trying to measure group size
#down to 1/1000th of an inch is a time-waster:

Ever been to a benchrest match?  They use dial calipers with a magnifying
sighting device, which has two arcs of the correct radius (1/2 bullet
caliber, which is typically .243").  The measurement is made to the
nearest 1/1000th of an inch, and having looked through it, I believe
this is repeatable to about that precision.  Even though you're
dealing with ragged torn holes in the target paper, the human eye
is capable of some pretty amazing interpolation, and centering.

In competitive BR, groups are measured to 0.001", and the average
of 5 groups is stated to four figures.

When I measure my own groups, I record three figures after the decimal
place.  Using regular dial calipers, I estimate that my measurement
is not good to 0.001", but it is definitely better than 0.010".  Why
throw away information at the measuring stage?  However, I will consider
a 0.453" 5-shot group to be the same darn thing as a 0.571" five shot
group (Statistics being the unkind beast that they are).

#    The mere fact that your dial caliper reads to 0.001" does not mean
#your measurement is that precise.  To measure this precisely, you must
#be able to visually discern when your calipers are oriented -exactly-
#parallel to the center-center line of the two holes, and then hold this
#orientation while making the measurement with -extraordinary- care.

It's not super critical.  Realize that the error created by not being
perfect here is related to the cosine of the angular amount that you
are in error.  And the cosine changes very little, for small error
angles.  If you're off by 2.5 degrees, your error will be 1 part in
1000.  This is a fairly large angle, that'll be easily detected visually.

#    Even if you could do this measurement with .001" precision, that
#-still- wouldn't mean your measure of group size is that accurate.  If

Yes it does.  It will be an accurate measurement of that group.

#you fired a number of groups from the same gun, I can practically
#guarantee you that they would not all agree to within .001 ".

This is true, but to determine the capabilities of a rifle, we
must record a large number of groups, without discarding information.

I refer to my Palma rifle as shooting "just a bit better than
5/8" 5-shot groups at 100 yards," even though I'll shoot groups
ranging from 0.4" to nearly 0.7" in a typical series of 10 5-shot
groups.

#    Maximum extent is a very poor quantifier for the type of
#statistical distribution one encounters in shot groups.

Unfortunately other metrics are not practical in most applications,
and yield little more information.

It's OK to use group sizes, but unfortunately most people don't
know just how large a grain of salt one has to take them with.

I keep thinking that a number of us in rec.guns should put our
heads together and write an article on applied statistics (w.r.t.
shooting), and publish it in Precision Shooting.  It is sorely
needed.

#    When have you >ever< run into a shooting situation in
#which placement was so critical that ( for example ) a gun with a
#0.500" group size would be acceptable and one with 0.501" not ?

Not field applications for sure, but if you're firing a BR match
it matters.


- Daniel