Home Forums Hunting & Shooting Ask The Gunwriters 3 shot groups vs 5? 10?

What's important to keep in mind in these discussions is the total number of shots, as well as how many per each group.

If you're talking about a single target, then more shots obviously give a better picture. That may be the context of the "seven shot theory", I don't know.

The question of how to best use a given number of shots, as in two 10s vs. 10 twos, is somewhat different.

Paul

The book I'm reading is "The Woodchuck Hunter" by Paul C. Estey.

His recommendation of two 10-shot groups was specifically aimed at load development for a varmint rifle, not zero checking, shooting practice, or high recoil rifles. Make 20 loads of each combination, fire 2 10-shot groups, then average them.

The trouble I see with ten 2-shot groups on separate targets is that the two holes may be close but shifting. The pairs move in relation to the aiming point but are still close together.

I have a problem with people who shoot a <1 inch group 6 inches from point of aim, then brag about their accurate rifle. I think it is a consistent or precise rifle, not an accurate one, until they can hit the aiming point.

Bruce

Three shot groups will give one a general idea of how well his rifle performs. If one wants some serious statistical evidence, then series of 20 shot groups would offer about the most economic and best sample size if one wants to quantify their dispersion around some point in space. T values, used to calculate confidence intervals in our statistics tables, decline very slowly once one exceeds a sample size of 20 or 21.

BCP: Good point that might be elaborated slightly. Accuracy relates to ones ability to hit a desired point. A rifle/shooter putting a 3" group around the bull is more accurate than a rifle/shooter who can do 1/4 inch groups 6 inches from the bull. The second shooter, however, is much more prcise than the first. If the second shooter can get his sights adjusted properly, then he will dominate in both (precision/accuracy) categories.

If you're an active shooter, you're gonna shoot them all.....one shot to test cold barrel POI;3 shots at all ranges to check zero;10 shots to test load consistency,etc etc. Is the accumulated knowledge from all kinds of shooting that gives you faith and confidence in your rifle,scope,load,etc

I personally want a precise rifle, I can always adjust the scope and get an accurate rifle.

It mostly depends on your mindset in such matters..Missing a woodchuck or Rockchuck to me is not very stressing...

I mostly use 3 shot groups for working up loads then when I get a 1/2 inch group (varmint rifle) I will fire some 5 shot groups and even a 10 shot at some point if I get the notions which I may or may not..I can't recall a rifle that shot 1/2 inch for 3 shots every going heywire on a 5 shot group and 99% of them shot within an inch or inch and a half with 10 shots..

I have shot several 10 shot groupd with my 6x45 5 pound walk about varminter and it shoots one hole every time and center to center is alway right at .300 and 3 shot groups are just a tad smaller at .270 average of 5 different 3 shot groups..It is my most accurate rifle in my life time..It is a miniture African big bore in design..kinda cute...

Don't know about the article in question, but here's a link to a pretty good discussion on 3 vs. 5 shot groups:

3 vs. 5 shot groups.

For a while, I used to stack two three and one four shot group on top of each other. It does seem to visually provide a much better feel for what a rifle is doing than just looking at the same groups separately.

John

When my DMPS put ten rounds into .85" at 100, I knew it was a shooter... when it did it again, I was like... yeah baby!

Then I sold the sucker. Sad ending.

Not surprising. Expected no less

I start with three shot groups. If they do will, then I retest with five rounds groups. I will test the five round group a total of two times.
This works for me.

Jim - There may have been an article that included the confidence level for the seven-shot group, but I did find what I referenced earlier. See Speer #13, p. 81, right column.

Excerpt:
"A single five-shot group is seldom adequate to give you an accurate picture of the quality of your ammunition. ... For best statistical confidence, five groups of five shots each is considered minimum. However, the cost of components mounts up quickly. A statistical analysis performed by the CCI-Speer Quality Assurance Section showed that a seven-shot group gave the highest degree of confidence with the fewest shots."

I think the reason I remembered the source for that quotation is that the Speer #13 was my first reloading manual, and the only reloading manual that I owned for a few years.

I aim for 0.5 inch three shot groups in all my rifles. Don't have one that doesn't.
What's important to me is that the gun consistently shoots 0.5 inch three shot groups and most importantly that first shot from a cold barrel is on the mark.

I check my rifles before every hunt at the range, I've been know to pick up an old favorite fire 1 or 2 shots, if it's 2 inches high and dead in line at a 100 yards; I'm just as likely to put it away, confident that if I miss it ain't the gun.

How about this? It tests POI, accuracy, and shooter. When I made a one click left adjustment (third row from top, third dot from left) the POI became perfect and they really started falling in there.

I shoot 5 "one shot" groups!

Dan

I like the way Ranch Dog does it on his levergun Postal Match. Fire 5 shots at one target. The score is determined by the one hole that is farthest from center. The closer to center, the better the score. Accuracy, precision, and shooter ability all rolled into one score. bxroads target shows the same things.

Having said that, I measure my deer rifle's ability with three shot groups.

-

3x3 shot groups that I call the shot as being good. If they are consistently around an inch or better I save them. Next time at the range I try the same load, again three or four 3 shot groups. If after I have 10 to 15 groups and they are mostly good with nothing strange going on I call it good to go and start shooting gongs and such from field positions.

I believe statistically a 10 shot group would be better, but this also gets into the "FOULED BORE" issue for some rifles. I believe the 10 shot group, even the 5 shot group that I prefer, has a considerable amount of "fatigue, eye drift and other shooter conditions that muddy the results if you are really developing a load for the the gun, and don't realize your 10 shot group is a combination of ammo quality, gun condition, and shooter ability....

A compromise may be to look at the 10 holes and determine which may be shooter influenced and weed them out. Group stringing, roundness and other conditions where you may have 2 good clusters can tell a lot , or baffle you....

I believe good record keeping, shoot many groups over a few months or many range trips, then lay all the targets out and decide from there which load is best. I have several pages of targets that prove one day a load did .75", and another target has a spread-out 1.5" group... either a fouled gun, poor marksmanship, poor weather conditions, guy next bench shooting a 300 Wby...... All add up to what drives some of us batty...lol

A friend told me a story that makes sense. When he did load development range day, he initially got out his 222 rem that shot .5" groups. He would determine if he would do load development, or have a play day by how well he shot the "GOOD GUN". Makes sense. If the overall conditions were not "right" he would know by the gun's group size....

Allen

3 shots is enough to zero the sights.
3 shots is enough to indicate where the rifle is shooting
3 shots is enough to indicate how good a particular load might be.
3 shot group can be smaller than the rifle actually shoots.
You move, and get lucky.

3 three-shot groups, averaged, gives a much better indication of rifle accuracy.

Group size at 100 yards does not extrapolate linearly to 200, 300 and 400 yards. Just because your rifle shoots 1 MOA at 100 yards, does not mean it will shoot 1 MOA at 200 or 300 yards. More likely, it will shoot 2 MOA.

If you expect to take a 300 yard shot, you need to shoot for groups at 300 yards from a bench. 10 shots from a cold barrel will indicate how good your rifle and ammunition are.

In the real world, you have no bench. So you have to shoot 10 shots from various positions at various ranges, to see what your limits are.

If you can't do better than 10 shots into 3 inches offhand at 100 yards, then 100 yards is your limit for offhand on big game.

If you can shoot 10 shots into 3 inches at 300 yards from sitting or prone, then you are good for that 300 yard shot hunting. If you can't put all 10 into 6 inches at 300 yards, then you have no business shooting at live game at 300 yards.

If you can shoot 20 shots into 1 MOA at 500 or 600 yards from prone, you can bet your rifle is shooting 1/4 MOA at 100 yards.

Remember that the question was "to test a load's accuracy". Shoot a target similiar to mine above and I'll guarantee you that it tells the tale.