Group Size

[Mystic Precision]

This is an old issue. In 1980 Creighton Audette presented a paper commenting on group size.

he said a 5 shot group would be 1.23 larger than a 3 shot group. And a 10 shot group would be 1.53 larger than a 3 shot group. And a 20 shot group would be 1.79 larger than a 3 shot group.

So, if you shoot a 3 shot group (and with a light hunting barrel, that might be all you can do) double it and you will be about right for knowing what the rifle can do.

Creighton was a leader in the area of rifle and ammo development and no shrinking violet when it came to debunking pet theories. he considered a single 10 shot group of little value and was contemptuous of anything less.

http://m14forum.com/accuracy/178649-excerpts-creighton-audette-article-group-size-probability.html

I wonder what he would find today given our much better optics, bullets, scales, brass prep and barrels???

Jerry

 

[IvoB]

Five shot groups show true potential of what a rifle/ammo can do. Flyers count make note on which shot it was 3-4 or 5th. If you find that's its your 4th shot constantly then it may be due to the magazine spring pressure. The first three rounds you have tight spring tension but the 4th or 5th not so much. If you find this happening try feeding them one at a time. It may just be something as simple as that. I take it a step further. I load 50 rounds all the same and shoot them on different range days to determine how good that load is.

You can go on and on - but find what works for you.

cheers
ivo

 

[RangerPark]

I use OnTarget TDS software when shooting many rounds at the range. I usually shoot 5 round groups at several target faces. OnTarget will superimpose all your target faces into a "virtual group", showing what your overall performance was that day. It's a real eye opener. After 10x 5 shot groups you get to realize that your .3 MOA 5 shots rifle simply isn't so. This is even more true for all manufacturers of rifles that "guarantee" a 1 MOA 3 shot group. Those rifles often aren't MOA rifles in real world conditions. It can be disheartening, but it's a reality check every shooter needs every now and then.

 

[kombayotch]

Have to agree with this more or less. I know when I started shooting (and still do sometimes) I get all tied up in group sizes but really they are not all that important for PRS type shooting.

A top shooter with a 1MOA gun would probably shoot the same score as with a .25MOA gun.

You can definitely shoot a match with a 1 MOA rifle and get most of the targets and yes top shooters will still do well, but a top shooter with a 1 MOA rifle will not be competitive against another top shooter with a 1/4 MOA rifle. Every point counts for top level shooters. Many matches have a good number of 1MOA targets and some have KYL racks with sub-MOA targets.

Here are some of the stages from Lone Survivor:



1 MOA at 1000 shooting WEAK SIDE! And yeah, he had a smaller plate out there next to it...



8 rounds, 4 plates... so possibly 5 shots on a 1 MOA plate at 1100



A 66% IPSC at 1160 is about 1 MOA wide.


2017 Finale had plate racks at 1400 that went down to sub-MOA plates...

 

[Mystic Precision]

Distance plays a huge role in hit percentage... 1MOA rifle at close range may be effective as there is less affect of the wind... but at LR, the effect is compounded.

We really see it in F class wrt to vertical outs. A 1/2 MOA vertical rifle at SR is not going to keep them in the 1/2 MOA V bull at 900m or 1000yds. There is simply too much dispersion, added to the wind drift, added to any shooter error.

Put another way, an accurate rifle has a very narrow cone of fire so there is wiggle room for wind and shooting error. If the rifle accuracy is pretty much the dimension of the target, you will need to make perfect shots EVERY shot to hit that target... I have yet to meet a shooter that can do that over the course of a match.

k, were these stages shot prone or off a prop of some kind?

Also, can you explain the stage 15 KYL stage... if you missed any of the larger targets do you then get a zero for score?.. or do you just try and hit the targets in order with the rds you have?

Jerry

 

[kombayotch]

Stage 15 was prone off a deck. Other two were quasi-prone off of barricades. "Bags, bipod and sling" means it was some form of barricade. Don't recall what stage 2 was, stage 5 was off a cargo trailer.

Stage 15 was a rack with 4 plates. You started on the largest one (2 MOA) and fired till you hit it. Once you hit it, you moved to the next one and did the same. Once you got to the smallest one (1 MOA) you fired the remainder of your rounds at it, hit or miss. So a person who cleaned the stage (and there were some) shot 5 shots at the 1 MOA plate. It was not a KYL.

 

[Mystic Precision]

That is some very fine shooting and condition reading

Jerry

 

[Mystic Precision]

With the popular chamberings used in PRS today, load work up really isn't that hard with a quality rifle and barrel. Except for 6 sighters and 2 foulers not shown, these are all the shots I have fired down my new Mcgowen Rem 783 barrel.

Each letter is a 0.2gr increase in powder... circled groups shot this morning, then a barrel cleaning, the other groups shot this afternoon. Light winds, overcast and drizzly.



Berger 140gr VLDs are one of my favorite bullets and this barrel love them too. With some careful adjustments, why wouldn't you want this level of accuracy? All groups shot at 200yds. These 2X3rds groups were shot back to back.

40rds fired so far... I think my load work up is done...

Jerry

 

[Ryan.M.Anderson]

Doesn't loan survivor have a very low average hit percentage? I thought it was one of the tougher matches around.

 

[kombayotch]

It's about average for hit percentage. Wind plays a big role in that. They have wind, but it's pretty consistent. We had some pretty generous targets a MLRSC last year and our hit percentage was lower than theirs because the winds are so switchy.

 

[Kechika]

great info here. thanks for the post