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The importance of group centering.

Part of the guru grumbles.


A question, do you know that every time you wind the sight, you alter the 
actual group centre?

It is crucial to ensure that the group is centered, and I reckon there are a few 
reasons to shoot at the "Fat part". The main one is to be able to take 
advantage of the size of the group by giving yourself the maximum area to 
play around in on the bullseye.
As we are aware, with the capabilities of the gear, and the ammunition far 
exceed the limitations of the measurements of the V bull and actual bullseye 
of our targets. The shooters of West Wallsend are very capable of shooting 
possible scores at any of the ranges back to 1,000 yards, and if the group is 
centered correctly, usually results in quite high V counts.
These high V counts are not an accident, they are reflections of the 
capabilities!
In coached matches, where the wind coach has control of the group centre, I 
think it is mandatory to ensure the wind and elevation knobs on the sight are 
used to maximise results.
The question above is very relative. Every time the knobs are twiddled, the 
group centre is adjusted, and it often takes five or six shots for this to become 
apparent on a plot sheet.
My work with the State and National Teams has left me extremely aware of 
how important this is, and of far more importance is the relative consistency of 
the wind zero’s of the respective rifles used by the members of the various 
teams.  In a team situation, where there are 5, 6, 10, or 15 shooters, you 
would be surprised at how consistent the group centering becomes when 
every shooter has virtually the same numbers on the wind arm!
It is crucial in a team to have correct wind zero’s, and to know the exact 
elevation numbers for each and every shooter for each and every distance, 
including the ranges we are shooting on.
This is one of the ways to maximise the ease of centering the group.

I would like to point out the high V count of the Westy team when we won the 
Josephson Teams match with a record score recently.
This was a product of an easy weather day and the group centering of the 
respective shooters.   I have had a good look at many of our team plots over 
the years, and it is significant that, at the Joso teams that Sunday, because of 
the easy day, the groups were centered smack in the middle.
(As a foot note here, because of the easy day we were able to discern that 
one of our shooters had a dysfunctional rear sight.) This became obvious 
when the plot sheets were analysed later.
 
In a wind coached situation, there are times when the group centre is adjusted 
to ensure that shot loss doesn’t become shot loss. The errant wind read shots 
may still be contained in the bullseye. This factor is decided when the wind is 
changing to velocity increase and so the higher wind velocity shots remain in 
the bull because the group is adjusted off centre a little.
There are a number of methods used with the wind knobs. One of these is to 
shoot quite fast, and adjust the shots by the position of the spotting disc in the 
V or Bullseye. Irrespective of this method, you are still adjusting the group 
centre every time the knobs are wound.  I saw Owen Pattinson win two 
Queens with this method. He shot them down there quite quickly, and if the 
spotters were moving to the sides or edge of the bull, he wound the sight and 
moved them back in. It worked well, and still does if you want to pursue the 
method. The clue is to shoot very fast with this method.

In all cases, you have to know where you fired the shot. It is important to 
nominate the shots to yourself and have the courage of your convictions.
It is obvious that if you shot a sudden 12 O’clock inner from an otherwise 
good group, and then moved the elevation down, you stand an extremely 
good chance of shooting a 6 o’clock inner for your next shot.  Particularly if 
the previous series of shots were good ones!  This is a facet of accuracy 
called error chasing, and I have seen many a shooter get into strife with this 
problem. Like I said, you alter the group centre when ever you move the sight.

Every shooter I know has a cone of hold. Some of them can easily hold the V 
ring and better at any distance.  Some of the elite shooters I know have 
extremely small group areas and can thus play around inside the central bull 
at their whim, adjusting the sight to retain the V bull as the shoot progresses.
Conversely, there are those around (and some of them quite good shooters 
too) that can only just maintain a group size inside the bull or even the inner 
ring.  These are the shooters that MUST be able to adjust the group centre all 
the time, otherwise, at some stage they will shoot the occasional inner purely 
because it was difficult to adjust the group centre. These shooters find it 
increasingly difficult if there is some wind about.  Some of them get frightful 
beltings, yet quite often you can see their scores come up to very high levels 
when shooting under a capable wind coach.

On difficult ranges, such as Canberra, where the wind changes are usually 
quite fast, it is often required that you move the wind arm back to zero and 
decide on the wind value out there before the next shot is released. Can you 
now see how important it is to have the wind arm correctly zeroed?
Canberra quite often has wind changes that result in crossing the zero line, as 
do many other ranges depending on the prevailing weather conditions.
In cases like this, it does not hurt to use the sighter shots to determine the 
extremes of wind value as this can give you a very good heads up indication 
of the adjustments to use in centering the group.
I saw a Queens won in New Zealand in 2001 where the shooter returned to 
zero then made the adjustment he thought was needed. John Whiteman won, 
but more importantly shot the whole Queens week over Trentham without 
losing a single point!  He took advantage of his knowledge, but had the 
courage to back it up. His attitude was incredible, and this too became an 
integral part of his commitment to what he was doing.

Group centering is extremely important, and for next Grade, which starts in a 
couple of weeks, I would like to see a plotter sitting up there with Alan 
Seaman.  The State Team, National Team and the various Sydney teams all 
use the extra man on the plot sheets.  This allows the coach a free mind to 
concentrate on his job.  It can only benefit the team, and we should give this a 
lot of thought, as part of the plotter’s mandate is to ensure the group is 
centered correctly.

Guru.

Last Modified -  12:11 8 Feb 2008