The whats what on groups

[JOE360]

Im assuming Bryan Litz dont mind the repost of his Facebook info here. But I think it's something that will help alot of people when there puzzled at the shooting or reloading bench.

 

[Tesoro]

I dont know about anyone else, but this makes me feel alot better!

 

[Dusty Stevens]

Hes pretty good at opening eyes with basic statistics. Really get a guy thinking

 

[Alex Wheeler]

Brian is a smart guy, but I cant agree with this if we are talking a good shooter and well built rifle. If you need 10 groups to be sure of something, something is wrong. I am always tuning a rifle, from a sporter to an elr rifle and do it with 3 shot groups and dont need to repeat tests unless conditions were terrible but I try to avoid that. I would like to think I get stuff pretty well tuned. Just think about that, you have to test, powder, seating, primers, neck tension, and if a component didnt work then all of it over with a new component. You would burn out the barrel before getting to a match or a hunt.

 

[INTJ]

Brian is a smart guy, but I cant agree with this if we are talking a good shooter and well built rifle. If you need 10 groups to be sure of something, something is wrong. I am always tuning a rifle, from a sporter to an elr rifle and do it with 3 shot groups and dont need to repeat tests unless conditions were terrible but I try to avoid that. I would like to think I get stuff pretty well tuned. Just think about that, you have to test, powder, seating, primers, neck tension, and if a component didnt work then all of it over with a new component. You would burn out the barrel before getting to a match or a hunt.

To your point, last match at Deep Creek I shot four consecutive 10-shot groups in the 5" range at 1000 yds over two days. I found that load with one 12-shot tuning ladder on Friday. That was the first time I had ever shot that bullet and that powder.

The way we tune in LR BR often produces results better than mine, so much so that it flies in the face of the statistical approach. But then again, most long range shooters seem to completely ignore why we do in LR BR..........

 

[Dusty Stevens]

To your point, last match at Deep Creek I shot four consecutive 10-shot groups in the 5" range at 1000 yds over two days. I found that load with one 12-shot tuning ladder on Friday. That was the first time I had ever shot that bullet and that powder.

The way we tune in LR BR often produces results better than mine, so much so that it flies in the face of the statistical approach. But then again, most long range shooters seem to completely ignore why we do in LR BR..........

Experience will tell you within a few groups what is junk and whats working. It also gives you a very good starting point like most BR shooters know about where the bullet they always use needs to be seated and they know within a few tenths of what powder is going to work. Thats the biggest difference in what we do and what hes referring to

 

[JEFFPPC]

Experience will tell you within a few groups what is junk and whats working. It also gives you a very good starting point like most BR shooters know about where the bullet they always use needs to be seated and they know within a few tenths of what powder is going to work. Thats the biggest difference in what we do and what hes referring to

Big advantage sticking to a cartridge and learning it as opposed to running to this year's latest and greatest after last year's latest and greatest did not work out for you.

 

[243BR]

Brian is a smart guy, but I cant agree with this if we are talking a good shooter and well built rifle. If you need 10 groups to be sure of something, something is wrong. I am always tuning a rifle, from a sporter to an elr rifle and do it with 3 shot groups and dont need to repeat tests unless conditions were terrible but I try to avoid that. I would like to think I get stuff pretty well tuned. Just think about that, you have to test, powder, seating, primers, neck tension, and if a component didnt work then all of it over with a new component. You would burn out the barrel before getting to a match or a hunt.

One "take away" I get is that Brian states the average SD is 30%. I suspect that with most BR rifles with accurately measured loads and hundreds of dollars worth of equipment on the bench top, the SD would be lower. But still, if you want an accurate assessment of a rifle/load, the higher the number of shots per group and the more groups the better. To me the trade off is more/large groups vs. barrel life and component cost/availability. I don't want to "shoot out" a barrel trying to figure out the perfect load.

 

[K22]

Speaking from a precision varmint hunting perspective shooting a moderate range, i.e., 300 yards and under, a couple of 5 shot groups has always revealed the potential of a satisfactory load that meets my standards (i.e., approximate 1/2 moa). Refining usually gets me to my objective then I stop and don't try to squeeze another .1" out of the load.

Testing that much in today's component costs and shortages would be prohibited for me but I understand that long range target shooters and precision hunters have more demanding requirements.

I've found the bullet selected has the most significant impact on finding a satisfactory load given using a powder suitable for the caliber you are loading.

JEEFPPC's comment of sticking with one cartridge has a lot of merit in my opinion. Get to know your rifle and cartridge.

 

[dgeesaman]

Brian is a smart guy, but I cant agree with this if we are talking a good shooter and well built rifle. If you need 10 groups to be sure of something, something is wrong. I am always tuning a rifle, from a sporter to an elr rifle and do it with 3 shot groups and dont need to repeat tests unless conditions were terrible but I try to avoid that. I would like to think I get stuff pretty well tuned. Just think about that, you have to test, powder, seating, primers, neck tension, and if a component didnt work then all of it over with a new component. You would burn out the barrel before getting to a match or a hunt.

I think you’re both right.

Brian is looking at what it takes to get statistical certainly, considering only statistics.

In load development, we know great loads are developed with high (not perfect) certainty using many fewer shots. We also know that there is value in saving barrel life, components, and that as a shooter we are less consistent over many shots due to fatigue and changing conditions. I know Brian is not immune to these things and it would be interesting to hear his thoughts on this.

Really, getting statistical certainty is not practical except in testing rimfire in a tunnel with a large budget.

 

[Beiruty]

Shooting a 6mm 109gr bullet in 24 lb BR rifle is not the same as
Shooting a 0.308 225gr bullet in 8 lbs hunting rifle with 90gr powder under it.

 

[memilanuk]

I've agonized over this off-n-on for years.

On the one hand, I've worked up some pretty successful loads using any number of popular methods, most of which promise some sort of maximum return for minimum rounds expended. As others have mentioned, a certain amount of familiarity / experience with a given cartridge goes a long ways when going this route.

On the other hand... I've been sorely disappointed by loads that gave every indication early on of being solid performers. I've learned the hard way to test and re-test before committing to a given 'recipe'. It might be shooting a local/club match - several 20 rd strings as opposed to five 10 shot groups, but the end result is the same.

As an aside... I've seen over the years a few accounts from people involved with testing guns, ammo, etc. from machine rests. Without fail, every report was that when you step back and take the human bias and 'reading of tea leaves' BS out of it... nothing grouped as well over the long run as people want to believe.

 

[CharlieNC]

Group size (extreme spread, range) does not conform to a normal distribution, so that is not the proper tool to use. There are better options to utilize to characterize "accuracy" and utilize to make predictions. Mean (average) radius is a start, and including the SD of the individual radia completes the picture.

 

[CA_Shooter]

Something I've seen is that people take things posted above by Brian, and then they add their own assumptions to it.

One result I have heard many say is that nodes do NOT exist and you can use any powder charge you want and with seating depth you will get it to be just as good as any other powder charge with some seating depth

 

[Alex Wheeler]

Shooting a 6mm 109gr bullet in 24 lb BR rifle is not the same as
Shooting a 0.308 225gr bullet in 8 lbs hunting rifle with 90gr powder under it.

It's not that far off. I have many threads on cartridges I have developed. Check the 300 saum imp. I just posted my complete load work on a 7.25 pound wsm.

 

[Beiruty]

Rifles could be either shooters or not.
A well designed and implemented rifle would shoot tight group.
Loading for rifle is more or less optimizing the ammo for the rifle.
A good rifle shooting 1/2 MOA groups consistently is golden in the hands of an expert shooter.
A rifle that shoots 1 MOA may shoot 1/2 MOA with optimized handloads, more or less, the handloads removed 1/2 MOA of ammo induced dispersion.

A good load, in good rifle, in the hands of an expert shooter, would produce its target precsion say 1/2 MOA, any day, any time.

What Bryan is stating is correct. The 5 shots groups are more or less meaningless statistically.
If you want to shoot many rounds and track your groups, use this online app

TARAN -- User Manual | guns@ptosis

guns.ptosis.ch

 

[jelenko]

Kind of on topic.
What does it mean that a 'well put together' rifle should shoot 1/2 MOA with any load?
What I mean is, what is the minimum that needs to be done to the rifle for that?

 

[rwj]

Group size (extreme spread, range) does not conform to a normal distribution,

What data set and test method(s) leads to this conclusion?

 

[Alex Wheeler]

Kind of on topic.
What does it mean that a 'well put together' rifle should shoot 1/2 MOA with any load?
What I mean is, what is the minimum that needs to be done to the rifle for that?

No rifle will do that. Even the best rifle will shoot big groups if you take it out of tune.

 

[JEFFPPC]

Rifles could be either shooters or not.
A well designed and implemented rifle would shoot tight group.
Loading for rifle is more or less optimizing the ammo for the rifle.
A good rifle shooting 1/2 MOA groups consistently is golden in the hands of an expert shooter.
A rifle that shoots 1 MOA may shoot 1/2 MOA with optimized handloads, more or less, the handloads removed 1/2 MOA of ammo induced dispersion.

A good load, in good rifle, in the hands of an expert shooter, would produce its target precsion say 1/2 MOA, any day, any time.

What Bryan is stating is correct. The 5 shots groups are more or less meaningless statistically.
If you want to shoot many rounds and track your groups, use this online app

TARAN -- User Manual | guns@ptosis

guns.ptosis.ch

Not in my world, might in yours.