And how much of this "group building" can be done with virgin brass. Or do we need to send another 50 or 100 rounds down the barrel to have "once-fired" brass?
“Your groups are too small” vs barrel life
- Thread starter nksmfamjp
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RegionRat
Well-Known Member
The old saying about "test it like you fly it" applies in ballistics....
Planning on only running with virgin brass?..., then test the difference in your cycled brass to see if it shoots the same. Maybe it does, maybe it doesn't. I have a few club mates who only shoot virgin brass, and they shoot a lot. (Other folks are lined up to buy their once fired brass.)
It certainly is nice when there is low or no difference between your processing of fired brass versus virgin. This doesn't always happen, but it certainly can.
In this thread, the whole theme is about "how many rounds and outings (condition changes) does it take to convince yourself you really know something is better, worse, same, different, etc..
I will throw in one more theme, and that is context matters. This forum is a hunting forum, so the first cold bore shot and maybe a follow up shot is all that matters. No sighters, no foulers, just "stand and deliver". The point of wasting those words, is the huge difference between most competitive shooting where "state of the art" is being defined, versus cold bore only.
How do we teach new young hunters (soldiers and SWAT) that is takes lots of rounds to define statistics, versus arriving at that well placed cold bore shot?
It seems to me that all one needs understand is what 3-5 shot group sizes will tell you and what they won't.
A 3 shot group can tell you what isn't working. If something isn't working, quit wasting components and try something else.
The fallacy with 3-5 shot groups is thinking that marginal differences are real. To determine if marginal differences are real requires more shots. Is it a question worth more shots?
No need to burn out a barrel.
A 3 shot group can tell you what isn't working. If something isn't working, quit wasting components and try something else.
The fallacy with 3-5 shot groups is thinking that marginal differences are real. To determine if marginal differences are real requires more shots. Is it a question worth more shots?
No need to burn out a barrel.
If I shoot 1 shot I have a 0 MOA group.
If I shoot 2 shots and they are .5 MOA apart I have a .5 MOA group.
If I stop there I think I am good.
If I shoot 10 more 2 shot groups and they vary from .5 MOA to 2 MOA I will see that the .5 MOA group was an aberration.
One 2 shot group might tell me something. A larger group size will tell me more. Multiple larger group sizes will tell me even more.
2 shots is not enough.
You are thinking about what I said in reverse...kinda.
Hypothetically let's say I'm looking for a .5" group at 100yds.....
If the first 2 shots are 2" apart then it will NEVER be a .5" group even if you shoot 5 times. That tells me that my rifle doesn't like that powder charge or seating depth or whatever ingredient I'm testing.
Now if the first 2 shots are touching then keep shooting to "prove" the load.
What I'm getting at is don't throw good money after bad! In load development I'm trying to figure what DOES NOT WORK in order to find what does work.
nksmfamjp
Well-Known Member
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I think there are some good points and some points that don't pass the statistical test.
First, we all agree we need 1-3 reliable shots to hunt game. That said we need reliable accuracy and precision. I don't know how to determine the probability of hitting my target without a reasonably rigorous statistically valid method.
Shooting an OCW iteration is normally a 5 shot by 5 target outing, but in reality, I only need t shoot until my target group size is blown. Like shoot 1-2 at target #1. If over 1", move on to load #2….maybe I get 3 before the group is blown. If all 5 blow the expected, maybe raise the expectation and keep shooting from group #1. This should reduce rounds fired.
On the idea that I only need 1 shot groups, that is a challenge. How do I know where that 1 shot is going without shooting a bunch of shots of the same load? Seems like this applies to 1-5 shot group shooters.
The Hornady method tells me to shoot 20 or 4 groups of 5, 7 groups of 3 and look at the composite group.. I think this works too, but no sense continuing to shoot if the group is blown. The problem with disregarding "the Hornady method" is that it is not the Hornady method. It is just the application of statistics to reloading/shooting. I don't think I can argue with the relevance of statistics to this sport.
First, we all agree we need 1-3 reliable shots to hunt game. That said we need reliable accuracy and precision. I don't know how to determine the probability of hitting my target without a reasonably rigorous statistically valid method.
Shooting an OCW iteration is normally a 5 shot by 5 target outing, but in reality, I only need t shoot until my target group size is blown. Like shoot 1-2 at target #1. If over 1", move on to load #2….maybe I get 3 before the group is blown. If all 5 blow the expected, maybe raise the expectation and keep shooting from group #1. This should reduce rounds fired.
On the idea that I only need 1 shot groups, that is a challenge. How do I know where that 1 shot is going without shooting a bunch of shots of the same load? Seems like this applies to 1-5 shot group shooters.
The Hornady method tells me to shoot 20 or 4 groups of 5, 7 groups of 3 and look at the composite group.. I think this works too, but no sense continuing to shoot if the group is blown. The problem with disregarding "the Hornady method" is that it is not the Hornady method. It is just the application of statistics to reloading/shooting. I don't think I can argue with the relevance of statistics to this sport.
My point exactly
VenatusDominus
Well-Known Member
First of all, this topic is totally irrelevant if you are shooting inside 400-500 yards. This topic was meant for those shooting at ranges where the bullet time of flight is over 1 second (around 1000 yards). The difference on between .5 MOA and 1 MOA accuracy matters not on an eight inch vital zone at 500 yards. At that range, establishing consistency of your load with 3-5 shots is plenty.
But consistency and statistical significant are not the same, and at 1000 yards the difference between .5 MOA (5.3 inch group) and 1 MOA (10.5 inch group) accuracy matters on an eight inch vital zone. At this range I want to know if the statistical probability of a shot landing within the 8 inch vital zone is 50% or 95%. You can absolutely establish consistency of a load with much less than 30 data points, but most statisticians agree that 30 data point is a minimum for establishing statistical significance, which is needed to produce valid probability percentages. Understanding math, science and statistics is not necessary to shoot inside 500 yards and many on this forum have no interest in, or even detest, them; I get that. But they become extremely important outside 1000 yards.
Second, the engineers/ballisticians at Hornady never advocated just shooting 30 shot groups. A three shot group can absolutely tell you, with confidence, if a load is not accurate, adding shots the group won't shrink it. But a tiny three shot group is never going to establish the true capabilities of a load, never! It certainly doesn't establish that you own a sub 1/4 MOA laser. The Hornady people recommended an initial 3-5 shot group using a reasonable powder charge and seating depth. If it doesn't meet your group size goals, then dump it and swap powder or bullet and repeat until arriving at a group size that meets your goal. Then shoot 20-30 in string sizes appropriate for your particular rifle/application (ie. 1-3 for hunting rifle, 10 for PRS or F-class). Plot the x and y coordinates (measured from point of aim) of each shot on a single graph and crunch the numbers to get a mean radius and standard deviation.
The engineers/ballisticians at Hornady postulated the following hypothesis:
Small changes in power charge and seating depth have inconsequential effects on accuracy over a large (statistically meaningful) sample size.
A writer at OutdoorLife, unaffiliated with Hornady, independently verified the hypothesis with regards to powder charge weight.
https://www.outdoorlife.com/guns/rifle-nodes/
Arguments against the hypothesis based on your deeply held religious beliefs about velocity or seating depth nodes, personal experiences with 3 shot groups, or because it contradicts or is different from "how you do it" are no more valid than the "because I said so" argument and make you look arrogant and unintelligent. If you want to disprove the hypothesis, the only valid way is to repeat the test yourself and present the data.
I would challenge the naysayers to shot a composite 30 round group (string sizes appropriate for your particular rifle/application) at your optimal seating depth and at the worst seating depth (within reason) from your ladder. I predict two things:
Note that mean radius and group size are not the same. Group size only considers the two worst shots. Mean radius considers every shot in the group. Take two 2" groups: The first a 30 shot group where 29 hit the same hole and one hits 2" out. The second all 30 shots are in a 1" donut around the point of aim. The mean radius of group one will be .067" (2/30") with one standard deviation (SD) of .36" and a 50% hit probability within .13" diameter, a 68% probability of hitting within .72" diameter and and 95% probability of hitting within a 1.4" diameter (2 SDs). The mean radius of group two is 1" and your hit probability is 100% within a 2" diameter (SD=0).
Establishing the mean radius of a group with a statistically significant data sample allows you to predict, with high confidence, where your bullet will land, if you do your part. Group size only tells you about your worst two shots.
But consistency and statistical significant are not the same, and at 1000 yards the difference between .5 MOA (5.3 inch group) and 1 MOA (10.5 inch group) accuracy matters on an eight inch vital zone. At this range I want to know if the statistical probability of a shot landing within the 8 inch vital zone is 50% or 95%. You can absolutely establish consistency of a load with much less than 30 data points, but most statisticians agree that 30 data point is a minimum for establishing statistical significance, which is needed to produce valid probability percentages. Understanding math, science and statistics is not necessary to shoot inside 500 yards and many on this forum have no interest in, or even detest, them; I get that. But they become extremely important outside 1000 yards.
Second, the engineers/ballisticians at Hornady never advocated just shooting 30 shot groups. A three shot group can absolutely tell you, with confidence, if a load is not accurate, adding shots the group won't shrink it. But a tiny three shot group is never going to establish the true capabilities of a load, never! It certainly doesn't establish that you own a sub 1/4 MOA laser. The Hornady people recommended an initial 3-5 shot group using a reasonable powder charge and seating depth. If it doesn't meet your group size goals, then dump it and swap powder or bullet and repeat until arriving at a group size that meets your goal. Then shoot 20-30 in string sizes appropriate for your particular rifle/application (ie. 1-3 for hunting rifle, 10 for PRS or F-class). Plot the x and y coordinates (measured from point of aim) of each shot on a single graph and crunch the numbers to get a mean radius and standard deviation.
The engineers/ballisticians at Hornady postulated the following hypothesis:
Small changes in power charge and seating depth have inconsequential effects on accuracy over a large (statistically meaningful) sample size.
A writer at OutdoorLife, unaffiliated with Hornady, independently verified the hypothesis with regards to powder charge weight.
https://www.outdoorlife.com/guns/rifle-nodes/
Arguments against the hypothesis based on your deeply held religious beliefs about velocity or seating depth nodes, personal experiences with 3 shot groups, or because it contradicts or is different from "how you do it" are no more valid than the "because I said so" argument and make you look arrogant and unintelligent. If you want to disprove the hypothesis, the only valid way is to repeat the test yourself and present the data.
I would challenge the naysayers to shot a composite 30 round group (string sizes appropriate for your particular rifle/application) at your optimal seating depth and at the worst seating depth (within reason) from your ladder. I predict two things:
- Your 7 pound, pencil barrel hunting rifle is not a 1/4 MOA shooter
- The mean radius of the two groups will not be statistically different; that,except in very rare cases (pun intended), small changes in seating depth make no difference. (The Horady engineers do state that in some bullets with very aggressive ogives, seating depth my marginally affect the mean radius of a group, they have not tested every bullet made.)
Note that mean radius and group size are not the same. Group size only considers the two worst shots. Mean radius considers every shot in the group. Take two 2" groups: The first a 30 shot group where 29 hit the same hole and one hits 2" out. The second all 30 shots are in a 1" donut around the point of aim. The mean radius of group one will be .067" (2/30") with one standard deviation (SD) of .36" and a 50% hit probability within .13" diameter, a 68% probability of hitting within .72" diameter and and 95% probability of hitting within a 1.4" diameter (2 SDs). The mean radius of group two is 1" and your hit probability is 100% within a 2" diameter (SD=0).
Establishing the mean radius of a group with a statistically significant data sample allows you to predict, with high confidence, where your bullet will land, if you do your part. Group size only tells you about your worst two shots.
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So what is your take on this video?First of all, this topic is totally irrelevant if you are shooting inside 400-500 yards. This topic was meant for those shooting at ranges where the bullet time of flight is over 1 second (around 1000 yards). The difference on between .5 MOA and 1 MOA accuracy matters not on an eight inch vital zone at 500 yards. At that range, establishing consistency of your load with 3-5 shots is plenty.
But consistency and statistical significant are not the same, and at 1000 yards the difference between .5 MOA (5.3 inch group) and 1 MOA (10.5 inch group) accuracy matters on an eight inch vital zone. At this range I want to know if the statistical probability of a shot landing within the 8 inch vital zone is 50% or 95%. You can absolutely establish consistency of a load with much less than 30 data points, but most statisticians agree that 30 data point is a minimum for establishing statistical significance, which is needed to produce valid probability percentages. Understanding math, science and statistics is not necessary to shoot inside 500 yards and many on this forum have no interest in, or even detest, them; I get that. But they become extremely important outside 1000 yards.
Second, the engineers/ballisticians at Hornady never advocated just shooting 30 shot groups. A three shot group can absolutely tell, with confidence, if a load is not accurate, adding shots to it won't shrink it. But a three shot group is never going to establish the true capabilities of a load, never! They recommended an initial 3-5 shot group using a reasonable powder charge and seating depth. If it doesn't meet your group size goals, then dump it and swap powder or bullet and repeat until arriving at a group size that meets your goal. Then shoot 20-30 in string sizes appropriate for your particular rifle/application (ie. 1-3 for hunting rifle, 10 for PRS or F-class). Plot the x and y coordinates (measured from point of aim) of each shot on a single graph and crunch the numbers to get a mean radius and standard deviation.
The engineers/ballisticians at Hornady postulated the following hypothesis:
Small changes in power charge and seating depth have inconsequential effects on accuracy over a large (statistically meaningful) sample size.
A writer at OutdoorLife, unaffiliated with Hornady, independently verified the hypothesis with regards to powder charge weight.
https://www.outdoorlife.com/guns/rifle-nodes/
Arguments against the hypothesis based on your deeply held religious beliefs about velocity or seating depth nodes, personal experiences with 3 shot groups, or because it contradicts or is different from "how you do it" are no more valid than the "because I said so" argument and make you look arrogant and unintelligent. If you want to disprove the hypothesis, the only valid way is to repeat the test yourself and present the data.
I would challenge the naysayers to shot a composite 30 round group (string sizes appropriate for your particular rifle/application) at your optimal seating depth and at the worst seating depth (within reason) from your ladder. I predict two things:
It is a win/win for everyone . You get some extra time at the range doing what we all love, you might learn something new and you can participate in the scientific method and help advance our shooting community. For those that are not comfortable crunching the numbers, I am happy to help with that at no cost.
- Your 7 pound, pencil barrel hunting rifle is not a 1/4 MOA shooter
- The two groups will not be statistically different, that except in very rare cases (pun intended), small changes in seating depth make no difference.
Huntnful
Well-Known Member
I like it, and I think they have the platforms to prove that differences can be made, as well as what those differences are, and the percentage that can be improved.
He also has a video showing a large sample size of his "best" and "worst" seating depths shot over 33 rounds, round robin, and there was no difference.
So in this video he put 20 rounds under 1 MOA with both depths at 600 yards. Looked like the worst depth was .8-.9 and the best depth was .6-.7? Shooting a 25 pound F class gun, with F class rifle rests. He's made videos barely proving, and also disproving the effects of small seating depth changes.
And we think we're going to do the same with our 8-10lb carbon barrel magnums with bipod and rear bag....
VenatusDominus
Well-Known Member
Once I think I have a good load I will go to our camp range fire 2 shots back to back first thing one morning when it's cool. Fire 2 more in the evening then repeat the next day. This will tell me a lot about cold bore consistency and temp change possibly affecting cold bore shots. It also gives me an 8 shot sample size to go with what I had during load dev. So at this point I will have 25-30 shots at least for data points. I also will fire two shots back to back during load dev. Then let the barrel cool fire 2 more etc. do this 5 times and essentially you have a 10 shot group that reflects a true hunting situation versus firing 2 5 shot groups.
jeb405
Well-Known Member
I looked through most of the posts but don't think anyone mentioned the theory behind sample size has nothing to do with shooting. I am in no way an expert on the subject but I believe for any data that is believed to follow a normal distribution in order for any statistics to have a confidence level 90% or more the usual minimum sample size is 30. If someone is better versed in this than I am please feel free to correct me.
In my experience the thing small groups lacks most is to account for the movement of POI between groups that will drive the group size higher.
I will not pretend to say I know what to believe. Shooters who win world championships don't use large group sizes. Yet the theory and the math say it will tell you more. Maybe the equipment, reloading and technique are so good the variation is very small so no matter the number of rounds in the group the team overall size does not change.
Don't think that would apply to me.
JB
In my experience the thing small groups lacks most is to account for the movement of POI between groups that will drive the group size higher.
I will not pretend to say I know what to believe. Shooters who win world championships don't use large group sizes. Yet the theory and the math say it will tell you more. Maybe the equipment, reloading and technique are so good the variation is very small so no matter the number of rounds in the group the team overall size does not change.
Don't think that would apply to me.
JB
In my experience being .003 from "ideal" is not a huge difference maker.
But there is a difference.
If being .003 from ideal makes groups go to hell, I'm not in a very stable zone, and I will keep changing depth until it appears I am in one.
Unless the gun has a problem it's very easy to see trends in your groups based on your adjustments.
And I'll bet the farm Keith was awfully close what he thought was ideal in that testing.
But there is a difference.
If being .003 from ideal makes groups go to hell, I'm not in a very stable zone, and I will keep changing depth until it appears I am in one.
Unless the gun has a problem it's very easy to see trends in your groups based on your adjustments.
And I'll bet the farm Keith was awfully close what he thought was ideal in that testing.
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