Thread: 10 Shot Groups

So in my test rifle thread @Roarless20 brought up he thought there was something mechanically wrong because some if the 5 shot groups are rather large (he very well may be right). He may be right and once I have a baseline accuracy for the rifle things like Bedding, action screws torque, recrown, etc will all be tested and eliminated. He may be right but I think some of the reaction is people actually don't know how well their rifle shoots especially over larger sample sizes.


Statistical variance suggests typically a 5 shot group will be around 1.3 times larger than a 3 shot group on average.

And a 10 shot 1.3 times what the 5 shot was on average.

From there it's slows only usually increasing around 1.2times for the 20 shot group and so on.

That would mean a 1moa 3 shot group is more like a 1.3moa 5 shot or a 1.7 10 shot or a 2 inch 20 shot. Likely representing a true rifle precision in the 2-2.5moa range. Off course any 3 shot group could be the closest 3 shots or the worst. But on average they are likely.

So I figured people could post up some 10 shot groups or more if you have done them. I highly recommend doing high sample size groups atleast once as its eye opening. If you have solved a mechanical issue with high round count groups that would be great data too as obviously that is a thing. I'm very familiar with the issues having owned enough kimbers that need the mag box floated and scope base screws shortened to solve issues.

The required precision for standard hunting ranges is not as high as people think and I took a rushed reload with a projectile the Tikka 223 kind of liked and a powder it ended up not liking at all that would produce a 3ish moa to the Forum shoot last year. All 20 shots where taken of a bipod without a rear rest and at the rate it takes to reacquire the target with a small break every five rounds to minimize mirage from the suppressor. It would likely be better with a rear rest.

At the shoot I did not find I was significantly handicapped.
I didn't place last and at that stage the 20 round zero probably maximimised my hit rate by ensuring I had the cone of fire centered.

I proceeded to make 1 correction to find the wind at 800 at the long range day Sunday and then made first round impacts out to 1100 on steel. All with a rifle most would hardly call precision. (Most shots fall in the centre of the cone)

So don't be embarrassed by "average" groups and put up what you get and what the rifle is.

Here's my embarrassing 20 rounder from the Tikka. (Shot in 5 round strings)



Here's the same rifle in the same session emptying a bunch of factory 50gr fiochi for the brass.



And only 10 shots this time but 10 shots of the 55gr fiocchi

Originally Posted by Stocky

So in my test rifle thread @Roarless20 brought up he thought there was something mechanically wrong because some if the 5 shot groups are rather large (he very well may be right). He may be right and once I have a baseline accuracy for the rifle things like Bedding, action screws torque, recrown, etc will all be tested and eliminated. He may be right but I think some of the reaction is people actually don't know how well their rifle shoots especially over larger sample sizes.


Statistical variance suggests typically a 5 shot group will be around 1.3 times larger than a 3 shot group on average.

And a 10 shot 1.3 times what the 5 shot was on average.

From there it's slows only usually increasing around 1.2times for the 20 shot group and so on.

That would mean a 1moa 3 shot group is more like a 1.3moa 5 shot or a 1.7 10 shot or a 2 inch 20 shot. Likely representing a true rifle precision in the 2-2.5moa range. Off course any 3 shot group could be the closest 3 shots or the worst. But on average they are likely.

Note that this correction factor applies to the AVERAGE group size. The AVERAGE 3-shot group size, established over enough groups to get a reasonably accurate mean, will increase by 15% to the AVERAGE size of 5 shot groups with the same system. A single group of less than 10 rounds tells you almost nothing, as the size varies wildly: 70% up or down from the average for 3-shot groups. Did you shoot a single 3-shot group at the minimum end, the average, or the maximum end? Who knows.

Originally Posted by Stocky

The required precision for standard hunting ranges is not as high as people think and I took a rushed reload with a projectile the Tikka 223 kind of liked and a powder it ended up not liking at all that would produce a 3ish moa to the Forum shoot last year. All 20 shots where taken of a bipod without a rear rest and at the rate it takes to reacquire the target with a small break every five rounds to minimize mirage from the suppressor. It would likely be better with a rear rest.

At the shoot I did not find I was significantly handicapped.
I didn't place last and at that stage the 20 round zero probably maximimised my hit rate by ensuring I had the cone of fire centered.

I proceeded to make 1 correction to find the wind at 800 at the long range day Sunday and then made first round impacts out to 1100 on steel. All with a rifle most would hardly call precision. (Most shots fall in the centre of the cone)

So don't be embarrassed by "average" groups and put up what you get and what the rifle is.

Here's my embarrassing 20 rounder from the Tikka. (Shot in 5 round strings)

Attachment 270350

Stocky shot better than me at the Sparrowhawk NZHS shoot, and I was using a rifle/load combo that shoots like this

Originally Posted by gimp

Stocky shot better than me at the Sparrowhawk NZHS shoot, and I was using a rifle/load combo that shoots like this

Attachment 270354

Plenty was luck that day.

Also I actually tend to think that even with a really precise rifle you might be better off with 15

Hey careful, this is getting into people's belief systems and you guys will get banned for religious talk . . . .

15 rounds with the Schultz and Larsen, used 80 gn ammo cause I have plenty. Previous 10 shot group coming next.



My notes show that this target was shot in very windy conditions, which is not the 223s strong point!

And I tested another 223, I'll make a separate post

It's a pity the 80 gn Sierra isn't a game getter, it shoots well in lots of rifles

Here is another 223's results, Zermatt Arms action, Hardy CF barrel in a CF stock - a good fun gun!



Couldn't find shot 15. Shot 2 is shot 2, dunno what happened, I get back spasms shooting prone but that didn't cause it.

And a 10 shot target



This is about as good as this rifle gets but it's utterly reliable at taking gongs 1 MOA and up at up to 4-500M. I often pass it to a young fella who is struggling a bit, a few 'hits' with it does their confidence wonders