ANY STATISTICAL OBSERVATIONS ?

[Bill Norris]

To be upfront and completely in search of an answer with my posting here, yes I understand a 30BR is a very forgiving round and easy to tune for the most part but I wanted to take a closer look at just exactly how precise/accurately my 30BR has shot over the time frame of working with it. These groups do not represent the total number of groups fired since load work-up from time to time over the past two years and in variable weather conditions was done but it does represent group sizes from the variety of different loads developed with different powders, bullets, primers and seating depths - no tuner on this rifle. I did try one neck tension test with one particular bullet and found that a .324 bushing was what the rifle wanted to shoot with that bullet. However, from a search back thru my records I cannot find a group that measured more than .388 after caliber deduction even during load development. I am no BR shooter and this is by no means a bragging post of my ability to shoot since my bench technique probably lacks a lot to be desired most of the time, but if bragging rights come into play it would be solely a contribution to (WSMNUT) ODCR - Zack Donovant for his ability to build nice rifles that shoot for even for the novice. I suppose if I have a question of what could be gained from the list is - How Many Years and/or How Many More Shots/Groups Would It Require To Statistically Prove What MOA My Rifle Shoots and it would be fantastic if Brian Litz and/or Hornady could chime in with their opinions. Please express your opinions on the statistical facts as you see it as well.

The format below is group size, number of shots in group, powder & charge for each bullet listed. Most of the loads used CCI-BR4 primers.

 

[Murray Brook]

Looks good Bill. Impressive #'s.

 

[Bill Norris]

Looks good Bill. Impressive #'s.

Thanks Bro.

 

[Murray Brook]

I have no experience with the 30 BR but looks like H 4198 is the go to powder for you.

 

[INTJ]

Bryan and Hornady are going to tell you you have a 1 MOA rifle because chances are that is you shot all those groups consecutively without sighters, you'd have a 30ish shot group that measures an inch at 100 yds. When you are oriented toward hunting, that is probably correct.

However, in BR we routinely shoot inside of statistical significance. We don't just blindly pull out or rifle and bang away. We careful consider all the variables and tweak our sight in based on conditions. All that leads us to shoot smaller groups in all types of BR than what the statisticians tell us we can do......

 

[Bill Norris]

I have no experience with the 30 BR but looks like H 4198 is the go to powder for you.

Absolutely.

 

[chkunz]

Typo in left column mid way down?

 

[22BRGUY]

To be upfront and completely in search of an answer with my posting here, yes I understand a 30BR is a very forgiving round and easy to tune for the most part but I wanted to take a closer look at just exactly how precise/accurately my 30BR has shot over the time frame of working with it. These groups do not represent the total number of groups fired since load work-up from time to time over the past two years and in variable weather conditions was done but it does represent group sizes from the variety of different loads developed with different powders, bullets, primers and seating depths - no tuner on this rifle. I did try one neck tension test with one particular bullet and found that a .324 bushing was what the rifle wanted to shoot with that bullet. However, from a search back thru my records I cannot find a group that measured more than .388 after caliber deduction even during load development. I am no BR shooter and this is by no means a bragging post of my ability to shoot since my bench technique probably lacks a lot to be desired most of the time, but if bragging rights come into play it would be solely a contribution to (WSMNUT) ODCR - Zack Donovant for his ability to build nice rifles that shoot for even for the novice. I suppose if I have a question of what could be gained from the list is - How Many Years and/or How Many More Shots/Groups Would It Require To Statistically Prove What MOA My Rifle Shoots and it would be fantastic if Brian Litz and/or Hornady could chime in with their opinions. Please express your opinions on the statistical facts as you see it as well.

The format below is group size, number of shots in group, powder & charge for each bullet listed. Most of the loads used CCI-BR4 primers.


View attachment 1422338

I'm sure you already have but I would average out each group with each powder, bullet.;
primer and other variables. Looks like you had a lot of enjoyment!
Very Nice shooting by the way.

 

[Bill Norris]

Bryan and Hornady are going to tell you you have a 1 MOA rifle because chances are that is you shot all those groups consecutively without sighters, you'd have a 30ish shot group that measures an inch at 100 yds. When you are oriented toward hunting, that is probably correct.

However, in BR we routinely shoot inside of statistical significance. We don't just blindly pull out or rifle and bang away. We careful consider all the variables and tweak our sight in based on conditions. All that leads us to shoot smaller groups in all types of BR than what the statisticians tell us we can do......

O K BUT, these groups were shot over a period of 2 years under varying conditions and temps.

 

[Bill Norris]

Typo in left column mid way down?

? Yea the dot is missing. Thanks.

 

[INTJ]

O K BUT, these groups were shot over a period of 2 years under varying conditions and temps.

I get that, but the other guys want to see all the groups shot to the same aim point with no adjustment so they can claim it's really only a 1 MOA group.

 

[Bill Norris]

I get that, but the other guys want to see all the groups shot to the same aim point with adjustment so they can claim it's really only a 1 MOA group.

Oh I see.

 

[INTJ]

The way the evaluate things is appropriate for a non precision field application like hunting, but it doesn't fit what we do in any type of BR

 

[Dave M.]

Absolutely.

I think I would have investigated the N130 more. Those groups are nothing to scoff at either.
Dave

 

[Bill Norris]

I think I would have investigated the N130 more. Those groups are nothing to scoff at either.
Dave

Still planning to work with it soon.

 

[Ray123]

I like the 115 gr Berger column and H4198 the 5 shot .037" group and the 10 shot .198" groups in particular ...exploit that area again, is what it says to me.

 

[jelenko]

Here's a calculator that will give you the required sample size to determine the value [i.e., group size] for a given confidence level and margin of error. https://www.calculator.net/sample-size-calculator.html?type=1&cl=95&ci=10&pp=50&ps=&x=72&y=22

For 95% confidence with a margin of error of 10%, you'll need 97 shots of the same load and, as mentioned, all at the same point of aim with no changes to set up.

For 95% confidence with a margin of error of 20%, you need 25 shots.

 

[Ccrider]

That is excellent record keeping and shooting. I think you get a better answer to your statistical question by averaging all of the groups fired of a particular developed load. Hopefully, @jelenko will figure the statistical value of the groups.

Which bullet and load have you found to be most consistent day in and day out, through various conditions?

 

[ebb]

Excellent groups!!! I agree with Dave. Load some for shooting and fun with H4198 and investigate V130 now that you have a load with H4198. See if with the different bullets it will make a better group than V130.

 

[dcali]

Given the number of variables and limited data, it's hard to say much more than "you're shooting in the 1s with high confidence".

There is no such thing as statistical proof. Only confidence. The more confidence you want, the more you have to shoot. There are different ways to measure groups, and some group sizes are more statistically significant than others. One trick to eke out a little more confidence is to average the vertical and horizontal group size, and use 5 shot groups (not 3 or 10). But to get high confidence in a truly independent test, you're going to need a lot of shots.

IF you use 5 shot groups, you can get to 90% confidence with a 20% margin of error in about 25 shots. If you use 3 or 10 shot groups, it will take about 28 (so really, 30, since you cant divide 28 by 3 or 10). 2 shot groups will take around 40. That's all for one load - the same powder, bullet, charge, etc.

That's nowhere near necessary for useful load development because nothing is independent in real life - that's just the formal math of it all - what you need to do to convince the mathematicians that you're rifle is "1/4 minute all day long".

If you're interested in this sort of thing, I wrote this article a while back.

Optimal Group Size for Rifles

Are 5-shot groups really better than 3-shot groups?

bisonballistics.com