Thread: 3 vs 5 shot groups

Originally Posted by ebf

The more shots in a group, the more sure you can be in your results.

10 shot groups are where it is at for REPEATABLE, consistent results

To be honest, the biggest variable in most group shooting to test stuff like seating depth, charge etc, is actually the shooter himself...

Three shots test the load. Five shots test the shooter. Not many shoots can consistently hold the same shoulder pressure in a hunting rifle for 5 shots.

Exactly. +! Taupohunter's comments.

Waiting for barrel to cool with 5s can mean altering positional pressures which can affect absolutely consistent point of aim. 3 shots less so.

3s can be ideal in sighting in process, checking POI.

How long for barrel cooling? I gave it 5 minutes the other day and results were good.

After I use factory or a generic book load to get on paper for a for brand new loads , eg new rifle, new caliber powder combo etc I also load 4 shots incase I can call one a flyer, however if after three and I can tell it's crap I don't bother with the last one. Take it home and pull it.
When satisfied and validating at 100m I load 8 and fire two distinct groups.
Might not be conventional but it's done me ok.

with the cost of ammo these days a 3 shot group is all it gets. if you are not shooting more than 400m then I don't see it being a big difference having a 5 shot group.

Ummm… maybe I’m over-simplifying it, but if you can’t decide or you’re not confident enough with 3 then use 4 shots.

When I have a 3 shot group with 2 close and 1 off, I can’t help wondering if I pulled the third. 4 shots with 3 close and 1 off I’m happy with the load and blame myself.

5 shots is just burning components, heating the barrel and tiring you out IMO. Dunno what the obsession with odd numbers is.

I am proud to say I have NEVER shot a group of five and then measured only the three best, as if they came out of a different rifle. Pure self-deception. You might say "The flyer was 'me'..." But then, who shot the others?

I prefer 2 shot groups,less barrel heating and when hunting you generally only use one one shot.Just last week i checked out my 308 tika2 with a minox 2x10x44 on it.It only been bore sight at 50yds last year so i thort il sight it in at a hundy and take it for a hunt.Just used 147gr fmj to make sure its on paper then shot some hornady ssts 150gr to get on bull.Close enough for deer i thort.I did let the barrel cool for 10 minuts between each group,and it was a cold day.

I think a whole lot of people fundamentally fail to understand the variability involved in shooting groups...

Interestingly enough the man himself posted this on Facebook a couple of days ago...

Quoted from Bryan Litz

One thing you learn when you shoot a lot of groups is the wide range of group sizes that are normal for a given rifle/ammo combo.

Many shooters seem to expect a gun to shoot basically the same group size all the time, but that's simply not how it works.

What we've seen over 100's of 5-shot groups from .223 thru .375 is that the standard deviation of 5-shot groups is about 30% of the average. Statistics tells us that 67% of groups will be between +/-1 SD of the average, and 95% of groups will be +/-2 SD's of the average.

So for example, if you're long term group average is 0.5 moa, then 67% of your groups will be between .35 and .65 moa. Likewise, 95% (19/20) groups will be between .2 and .8 moa. Anything in that range is completely normal for a .5 average.

Originally Posted by ebf

I think a whole lot of people fundamentally fail to understand the variability involved in shooting groups...

Interestingly enough the man himself posted this on Facebook a couple of days ago...

Quoted from Bryan Litz

One thing you learn when you shoot a lot of groups is the wide range of group sizes that are normal for a given rifle/ammo combo.

Many shooters seem to expect a gun to shoot basically the same group size all the time, but that's simply not how it works.

What we've seen over 100's of 5-shot groups from .223 thru .375 is that the standard deviation of 5-shot groups is about 30% of the average. Statistics tells us that 67% of groups will be between +/-1 SD of the average, and 95% of groups will be +/-2 SD's of the average.

So for example, if you're long term group average is 0.5 moa, then 67% of your groups will be between .35 and .65 moa. Likewise, 95% (19/20) groups will be between .2 and .8 moa. Anything in that range is completely normal for a .5 average.

Well said to you both. This exposes the sheer folly of selecting a load based on one three shot group.
Regards Grandpamac.

When testing things like seating depth, if you dont like what you see after firing two shots, ie they are further apart than what you're after, you might as well stop there and not fire any more shots of that group, as a third, forth or fifth isnt going to make the group any smaller.

Might as well move onto shooting the next test group, if you're happy with the first two then shoot a third, if not stop after two and move on.

Originally Posted by small_caliber

Are you saying that selecting a good load based on 3 shot groups is not achievable?

It seems I disagree with you if that is what you are saying, It seems that when it comes to the accuracy shooting sport, Benchrest, the majority develop their load by firing 3 shot groups, even Tony Boyer tunes using 3 shot groups, try reading his book, The Book of Rifle Accuracy.

No I believe he is saying that relying on 1x 3 shot group is not enough, ie if you get a single load that shoots a good 3 shot group load some more up and confirm it, as it's easy enough to fluke 1 good group. There's a lot more to it than that but I'm not gonna sit here and tell everyone how to suck eggs.

Originally Posted by small_caliber

Are you saying that selecting a good load based on 3 shot groups is not achievable?

It seems I disagree with you if that is what you are saying, It seems that when it comes to the accuracy shooting sport, Benchrest, the majority develop their load by firing 3 shot groups, even Tony Boyer tunes using 3 shot groups, try reading his book, The Book of Rifle Accuracy.

Greetings@small_caliber,
The important point was one or a single three shot group. Testing a promising load with more three shot groups will either validate the first group or demonstrate that it was a fluke. with a single group you will never know.
Regards Grandpamac.