Follow up to first load development

[Shooterdevil]

So a followup to my load development for my ruger precision rifle in 6.5 creedmoor. This time I decided to zero at the same time and knock two birds with one stone. Honestly, I really dont notice any difference among the overall groups. I'm getting to the point where the data is slightly off and I'm just going to choose the load that gave me the smallest group and most recent best SD.

Here are PREVIOUS 5 loads 5 shots each with average velocity and SD
Grain Average Velocity SD
40.5 2598.2 22.77
40.7 2619.0 11.20
40.9 2630.8 15.51
41.1 2629.6 10.43
41.3 2646.8 23.05

Today's Load
40.5 2585.6 15.74
40.7 2594.2 15.29
40.9 2619.6 12.64
41.1 2633.8 21.82
41.3 2651.4 08.85

The only difference between todays load and previous is the bullet is seated roughly .02" off the lands for the most recent load, using the OAL gauge to determine bullet seat depth, and the previous load had SRP while the recent loading had SRP magnum.

The only head scratcher is the difference in SD for the two 41.3 loads, previous being 23.05 and recently being 08.85.

Below are the last 10 rounds I shot (5 from 41.1 and 5 from 41.3), the first 15 were for zeroing, which from the looks of it now I could probably use one more elevation adjustment and itll be good to go. I THINK the smaller group was the 41.1 but the idiot that I am I forgot to mark which was which. Honestly the difference is so small it doesn't really matter at this point.

Be gentle, this is my first groups ever at 100 yards with a bolt action.

 

[bozo699]

If you haven’t hit pressure I would bump up your charge you’re not in tune yet. You have 2 groups within each group
Wayne

 

[Shooterdevil]

If you haven’t hit pressure I would bump up your charge you’re not in tune yet. You have 2 groups within each group
Wayne

Sorry, could you elaborate?

 

[NZ_Fclass]

Im assuming that you are shooting a 140g with 4350, looking at the loads. I would not be too concerned at this point. The velocities are where you would expect and the groups are OK. The rifle is fairly new? and this is the first time shooting this brass? Shoot some more - it may just be temperature variation or loading technique. Dont worry about figures - see what the target tells you. Pick a primer, and stick with it for now. Do a ladder test and find the nodes with 5 shot groups, then retest the good groups with 10 shot groups. I would also move the bullet a bit further back - maybe 12-15 thou off, and drop 2 the lower velocity loads. I started my 6.5 load testing at 41g. Watch F-class John and Keith Glasscock on ladder testing, always worth your time.

 

[Doom]

So a followup to my load development for my ruger precision rifle in 6.5 creedmoor. This time I decided to zero at the same time and knock two birds with one stone. Honestly, I really dont notice any difference among the overall groups. I'm getting to the point where the data is slightly off and I'm just going to choose the load that gave me the smallest group and most recent best SD.

Here are PREVIOUS 5 loads 5 shots each with average velocity and SD
Grain Average Velocity SD
40.5 2598.2 22.77
40.7 2619.0 11.20
40.9 2630.8 15.51
41.1 2629.6 10.43
41.3 2646.8 23.05

Today's Load
40.5 2585.6 15.74
40.7 2594.2 15.29
40.9 2619.6 12.64
41.1 2633.8 21.82
41.3 2651.4 08.85

The only difference between todays load and previous is the bullet is seated roughly .02" off the lands for the most recent load, using the OAL gauge to determine bullet seat depth, and the previous load had SRP while the recent loading had SRP magnum.

The only head scratcher is the difference in SD for the two 41.3 loads, previous being 23.05 and recently being 08.85.

Below are the last 10 rounds I shot (5 from 41.1 and 5 from 41.3), the first 15 were for zeroing, which from the looks of it now I could probably use one more elevation adjustment and itll be good to go. I THINK the smaller group was the 41.1 but the idiot that I am I forgot to mark which was which. Honestly the difference is so small it doesn't really matter at this point.

Be gentle, this is my first groups ever at 100 yards with a bolt action.

You have two separate tests and two standard deviations. To understand what is going on you have to understand how to analyze and understand how to analyze and compare test statistics. In this case if we look at the confidence interval for the 8.85 SD for 5 shots the 95% confidence interval is 5.3 to 25.4 fps. If you would calculate the confidence interval over an infinite number of samples with a sample size of 5, 95% (CL) of the calculated confidence intervals will contain the standard deviation's true value, and 5% (α) of the calculated confidence intervals will not contain the standard deviation's true value. Similarly for the 23.05 the range is 13.8 to 66.2

If you do an F-Test to compare the two test there is 95% confidence that the the tested 8.85 is less than the 23.05.

What the analysis says is that you have two test with different results. The wide range of confidence intervals indicates that neither set of data has enough data to conclude that one set represents a statisticcally significant difference.

 

[rdb8847]

Are you guys using Minitab for data analysis and statistics?

 

[Zero333]

40.5 to 41.3 is only a 0.8 gr spread.
No wonder you might not see any variation in group size.

If a factory barrel is shooting 1/2 moa consistently I would be plenty happy anyways.

 

[Doom]

Are you guys using Minitab for data analysis and statistics?

During my working years I mostly used tools that were self developed but used SAS in years gone by. I found this site a year or so ago that has a lot of narration so I tend to use it most of the time. It helps explain the various methods and saves time when I run data for others.

I haven't checked all the algorithms but the ones I use F-Test, Welch's T Test, confidence intervals, have all be checked.

Statistics online - checks assumptions, interprets results

Statistical tests, charts, probabilities and clear results. Automatically checks assumptions, interprets results and outputs graphs, histograms and other charts.

www.statskingdom.com

 

[Doom]

40.5 to 41.3 is only a 0.8 gr spread.
No wonder you might not see any variation in group size.

If a factory barrel is shooting 1/2 moa consistently I would be plenty happy anyways.

Those of us that use OCW normally find that our "nodes" typically occur on ~3% load increments or about 1.2gr increments in a 308 or similar sized case. There is some speculation/theory that it can occur on 1.5% intervals and I have seen one case personally where this occurs. Prior to using Gordon's Reloading Tool I would usually work from 95% of maximum load to maximum (shoot single rounds for pressure check from 90% to 95%).

 

[Zero333]

Like @Doom said:.. you need to cover at least 1.5 gr to see a big difference.
But if you're already shooting 1/2 moa with a factory barrel I would just try to repeat the results and if they're the same I'd leave it alone. Maybe play with seating depth, but I wouldn't waste my time.

Just shoot and have fun.
Ruger Precision rifles are PRS type rifles and not for made for benchrest

 

[Doom]

@Zero333 brings up a good point that often gets overlooked and probably should be said more often. People that post group sizes often quote tiny 3 or 5 shot cherry picked group sizes, and from god only knows what rifle, rest, etc, is used. Heavy Benchrest rifles weigh near 30 lbs, have triggers with pull weighs measured in ounces, and shot from rests that cost as much as high end optics. Then there are AR service rifles that weigh just under 14 lbs. F Class 22 lbs, F-T/R 18 lbs. It is a mistake to think a 6.5 lb hunting rifle, a 6-7 lb AR-15, or 10-12 lb tactical rifle or varmint rig is going to produce tiny drops of these specialty rifle. It is critical to have realistic exceptions for the equipment used.

 

[Homerange]

@Zero333 brings up a good point that often gets overlooked and probably should be said more often. People that post group sizes often quote tiny 3 or 5 shot cherry picked group sizes, and from god only knows what rifle, rest, etc, is used. Heavy Benchrest rifles weigh near 30 lbs, have triggers with pull weighs measured in ounces, and shot from rests that cost as much as high end optics. Then there are AR service rifles that weigh just under 14 lbs. F Class 22 lbs, F-T/R 18 lbs. It is a mistake to think a 6.5 lb hunting rifle, a 6-7 lb AR-15, or 10-12 lb tactical rifle or varmint rig is going to produce tiny drops of these specialty rifle. It is critical to have realistic exceptions for the equipment used.

Yet with careful load development most modern rifles can achieve 1/2 MOA with hunting loads that satisfies the needs of realistic owners.

 

[bozo699]

Yet with careful load development most modern rifles can achieve 1/2 MOA with hunting loads that satisfies the needs of realistic owners.

I have to agree with Zero333 and Doom’s analogy. I have had a couple factory sporter rifles that would shoot 1/2 moa on a regular basis (3 shots) not 5 or 10 like we do in br but it’s not the norm. There’s lots of folks out here that cherry pick there groups, they get one quarter inch group and they pack it around in there wallet telling everyone there model 99 .300 savage is a quarter inch gun!… if that were the case and true then why do we spend 1000’s building rifles to shoot in the 2’s?…..
Wayne

 

[jelenko]

I have to agree with Zero333 and Doom’s analogy. I have had a couple factory sporter rifles that would shoot 1/2 moa on a regular basis (3 shots) not 5 or 10 like we do in br but it’s not the norm. There’s lots of folks out here that cherry pick there groups, they get one quarter inch group and they pack it around in there wallet telling everyone there model 99 .300 savage is a quarter inch gun!… if that were the case and true then why do we spend 1000’s building rifles to shoot in the 2’s?…..
Wayne

I think some/many see a 1/4 MOA group and conclude that their rifle will do that if they do their part.

 

[fkimble@charter.net]

As Bozo said you have 2 groups within each 5 shot grp. But what I see is shots 1,2 & 3 together then shots 4 & 5 together. Called double grouping. When its always the last shot or two out of the group, my first thought is shooter error. Not getting set up on bags correctly for those last shots, recoil/flinch on a light weight full caliber round. On a light weight sporter barrel, could even be heat related if firing too fast. Something loose such as scope base or rings or reticle, but this usually shows as shots alternating in the 2 groups. With only 2 samples its hard to determine.
For a factory barreled gun, I would be happy and pick one load and go hunting, shooting what ever you want to do with the gun!

Frank