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what do groups mean?

 
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  #1  
Old 03-16-2011, 09:27 AM
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Join Date: Mar 2004
Location: n.w. pennsylvania
Posts: 90
what do groups mean?

i know this has been discussed before, but i cant find it when i do a search...

what do different group shapes mean?

ex. if all shots are vertical, horizontal, triangle?
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  #2  
Old 03-16-2011, 11:22 AM
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Location: Blackfoot, Idaho
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Re: what do groups mean?

Ur gonna open a can of worms with this one, I'm bettin'. There will be plenty of subjective responses and personal experience. All responses will be good for consideration.

Initial considerations/assumptions upon which my "experience" is based.

  1. the right load
  • Correct combination of powder/primer/bullet/seating depth that particular rifle.
  1. Rifle is 'properly' bedded
  • action is bedded
  • barrel is bedded up the chamber (2" or so)
  • barrel is free floated from there to the end OR
  • barrel is bedded to the end of the forearm.
  1. Proper bore cleaning regimen.
  1. Scope properly mounted AND
  • Focus and parallax properly adjusted
  1. Proper shooting skill have been developed.
THEN: Many many times I have seen '|" shaped groups turn into '--' shaped groups with the addition or subtraction of a few grains of powder. When that happens I try various powder charges somewhere around half way between these two charge weights and nearly always end up with a '.' shaped group.

In even more words when I get a nice small vertical string I add powder. 2 grains or so in for an example rifle (uses 100 grain charges) if the result is a horizontal shaped group, I reduce the load by a grain and can bet that the resulting group will approach a uniform 3 shot triangle shape. This usually works.
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Old 03-16-2011, 11:53 AM
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Re: what do groups mean?

Roy, thanks for the reply and info....

Ideally... what kind of group would be best?

I shot a new load this week at 200yds.. (4 shots) had 3 touching vertically, and the 4th was to the right of the top of the vertical string.. all shots were touching... very happy with .7'' group at 200 yds.. just curious if i should play with anything
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Old 03-16-2011, 12:25 PM
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Location: Blackfoot, Idaho
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Re: what do groups mean?

Before finding LRH.com I would have suggested 'go for the one holer.'

I suffer from major "tinkeritus" and have worn out perfectly good barrels playing around.

At this point in a long life I'd say stick with that load, don't mess with it at all!!

The math says that you are, with that group as an example, hitting within 0.35" of POA at 200 yards or 0.175 MOA. Figure how far that will make you rifle effective. It's a right fur piece!!!

This is where I would work up the drop chart for that load then shot in cold bore every once in awhile and go from there.

What are the details of this rig that is being so accurate?
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Old 03-16-2011, 01:19 PM
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Re: what do groups mean?

"Ideally... what kind of group would be best?"

A single round hole of bullet diameter.
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  #6  
Old 03-16-2011, 02:08 PM
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Join Date: Mar 2004
Location: n.w. pennsylvania
Posts: 90
Re: what do groups mean?

boomtube... not really the answer I was looking for


Roy.. this gun is a REM 700P bought back in 2003. Just got back into shooting LR last year after taking a few years off and started working on better loads for it.

300 WM, only work done is trigger
sightron SII 6x24
72.4 gr of reloader 22
190 berger VLD
just touching lands.
winchester brass

have had several loads shoot at or better than .75 moa, then I shot this load mon at 200yds and it was very tight (less than.5 moa)
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  #7  
Old 03-17-2011, 09:09 AM
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Join Date: Jun 2010
Posts: 372
Re: what do groups mean?

It depends on the rifle. My LRH shoots triangular groups with any load where my Husquvarna 6.5-284 strings loads when deviation is too much. I have a Model 100 Winchester that shoot unbelievably well, but every different bullet will group in random areas in relation to point of aim and will require adjustment for Zero. One load may be dead on and 1/2 inch dead center, switch to another bullet of the same weight and it can shoot as much as 8 inches left or right. This may not help much but the main thing I have noticed is that there is no rule that applies with EVERY rifle.
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