New load development combo method, what do you think?

[Sraw]

For those who haven’t seen my previous thread, I am in search of the most efficient load development method.

I have experimented with the Satterlee “10 round” load development and worked it a little further. I think it has a place, and even though it worked in my case, I think it was fairly coincidental and leaves a lot of room for error.

What I decided to do was take several recommendations along with some known techniques such as the Cortina method and OCW and combine them with an extended “10 round” load development, in my case 39.

I shot 3 of each load from 40.2-42.6 in .2 incriminates at 100 yards, shooting each group on a separate target, measuring (then graphing) velocity, and lastly comparing impact location of the groups.

I was shooting 6.5 Creedmoor in a factory Savage Stealth. The components were Hornady 143 ELD-Xs, Lapua Brass, H4350, and CCI SRM Primers.

The bullets were seated .020 off the lands but I had to file down the inside front of the magazine to do so and a couple still got hung up. It seems an investment in a longer OAL magazine is in order.

I am not ruling out shooter error in some of these groups and am pretty sure I am responsible for the low shot on the 41.4 group.

I know they were only 3 shot groups and not 5, 9, or the 20 round groups that some of you use but remember this is step one of an “efficient” load development.

The first and last groups were me testing Hornady’s Precision Hunter.

In my opinion based on a combination of all three data points, the load that currently shows the most potential is 42.1. ES and SD look great, There is an ES of 9 FPS between of 42.0 and 42.2. The groups are good on either side of it, could improve with seating depth adjustment. And the two groups on either side hit close to each other vertically from the point of aim.

41.3 also seems promising if for whatever reason 42.1 didn’t work out.

So far this method has used 39 loads. As I learn this rifle I believe I started too low and could have started at 41.0, saved 12 shots and still been happy with the results. I didn’t hit any pressure signs so those may have been better served on the other end as anything below 2700 wasn’t considered.

My next plan in the process it to load 10 at 42.1 and shoot 5 with a chrono to confirm speed, ES, and SD, and shoot 5 without to confirm grouping.

That puts my load development just inside of 50 rounds, would have been less than 40 if I wouldn’t have started so low. I’ve also considered going up in .3gr incriminates to cover more ground faster.

Depending on my results I then plan to adjust seating depth if necessary.

One thing I am considering for next time is to try out a single load per charge ladder test going up until I find pressure signs. From there try this method using less loads over the velocity spot I am trying to achieve.

As always, please feel free to provide any insight, advice, or suggestions going forward.

The results were as follows:

40.2- 2666, 2670, 2677 ES-11 SD-5

40.4- 2699, 2692, 2685 ES-13 SD-6

40.6- 2692, 2690, 2701 ES-11 SD-5

40.8- 2708, 2708, 2704 ES-4 SD-2

41.0- 2718, 2722, 2731 ES-13 SD-6

41.2- 2731, 2731, 2737 ES-6 SD-3

41.4- 2739, 2744, 2736 ES-8 SD-4

41.6- 2750, 2754, 2745 ES-9 SD-4

41.8- 2762, 2775, 2758 ES-17 SD-8

42.0- 2778, 2774, 2773 ES-5 SD-2

42.2- 2779, 2774, 2782 ES-8 SD-4

42.4- 2802, 2791, 2805 ES-14 SD-7

42.6- 2815, 2808, 2809 ES-10 SD-5

 

[memilanuk]

Looking better...

Something about that graph just seems... noisy. Kinda hard to pick out anything from that jagged line. Maybe something more like this, where the individual velocities are the '-' marks (to give a feel for the variance at each step along the way) and the continuous line(s) for the average / median speeds (looking for a 'plateau')


And something like this to kind of drive home how the vertical center of the groups are tracking:



Both of which look like they point at that 42.1 range, as you already mentioned.

Take a look at the attached spreadsheets; you might find it of interest. FWIW, it's not my creation; it's from a ".308 Win / 7.62x51 Reloading" group on FB. Pretty well fleshed out, though you do need to have a bit of a knack for manipulating charts and images in Excel if you want to do the full 'bling' workup

 

[comagutsa]

nice work mate

 

[JFrank]

View attachment 1073587 View attachment 1073590 View attachment 1073591 View attachment 1073592 For those who haven’t seen my previous thread, I am in search of the most efficient load development method.

I have experimented with the Satterlee “10 round” load development and worked it a little further. I think it has a place, and even though it worked in my case, I think it was fairly coincidental and leaves a lot of room for error.

What I decided to do was take several recommendations along with some known techniques such as the Cortina method and OCW and combine them with an extended “10 round” load development, in my case 39.

I shot 3 of each load from 40.2-42.6 in .2 incriminates at 100 yards, shooting each group on a separate target, measuring (then graphing) velocity, and lastly comparing impact location of the groups.

I was shooting 6.5 Creedmoor in a factory Savage Stealth. The components were Hornady 143 ELD-Xs, Lapua Brass, H4350, and CCI SRM Primers.

The bullets were seated .020 off the lands but I had to file down the inside front of the magazine to do so and a couple still got hung up. It seems an investment in a longer OAL magazine is in order.

I am not ruling out shooter error in some of these groups and am pretty sure I am responsible for the low shot on the 41.4 group.

I know they were only 3 shot groups and not 5, 9, or the 20 round groups that some of you use but remember this is step one of an “efficient” load development.

The first and last groups were me testing Hornady’s Precision Hunter.

In my opinion based on a combination of all three data points, the load that currently shows the most potential is 42.1. ES and SD look great, There is an ES of 9 FPS between of 42.0 and 42.2. The groups are good on either side of it, could improve with seating depth adjustment. And the two groups on either side hit close to each other vertically from the point of aim.

41.3 also seems promising if for whatever reason 42.1 didn’t work out.

So far this method has used 39 loads. As I learn this rifle I believe I started too low and could have started at 41.0, saved 12 shots and still been happy with the results. I didn’t hit any pressure signs so those may have been better served on the other end as anything below 2700 wasn’t considered.

My next plan in the process it to load 10 at 42.1 and shoot 5 with a chrono to confirm speed, ES, and SD, and shoot 5 without to confirm grouping.

That puts my load development just inside of 50 rounds, would have been less than 40 if I wouldn’t have started so low. I’ve also considered going up in .3gr incriminates to cover more ground faster.

Depending on my results I then plan to adjust seating depth if necessary.

One thing I am considering for next time is to try out a single load per charge ladder test going up until I find pressure signs. From there try this method using less loads over the velocity spot I am trying to achieve.

As always, please feel free to provide any insight, advice, or suggestions going forward.

The results were as follows:

40.2- 2666, 2670, 2677 ES-11 SD-5

40.4- 2699, 2692, 2685 ES-13 SD-6

40.6- 2692, 2690, 2701 ES-11 SD-5

40.8- 2708, 2708, 2704 ES-4 SD-2

41.0- 2718, 2722, 2731 ES-13 SD-6

41.2- 2731, 2731, 2737 ES-6 SD-3

41.4- 2739, 2744, 2736 ES-8 SD-4

41.6- 2750, 2754, 2745 ES-9 SD-4

41.8- 2762, 2775, 2758 ES-17 SD-8

42.0- 2778, 2774, 2773 ES-5 SD-2

42.2- 2779, 2774, 2782 ES-8 SD-4

42.4- 2802, 2791, 2805 ES-14 SD-7

42.6- 2815, 2808, 2809 ES-10 SD-5

As always I'm probably the minority however my question is - what's wrong with 41.2 -41.6

 

[Alex Wheeler]

Looks like your just shooting groups and noting poi and groups size and velocity. Thats good and it what you should do. Thats standard load development. One thing to note on small sample sizes, look at trends. 3 shot groups are plenty for load work. There should be a trend, the groups getting smaller then larger again. If you are not seeing a smooth trend then change a component like powder. Random sized groups that have erratic shapes or poi tell me the powder/bullet/primer combo is wrong. If you had an extremely accurate rifle with the right powder/bullet/primer combo, one shot "groups" would get you real close just by looking at poi. There is a lot to learn from your groups, poi, shape, size, and the trend. I would say your pretty close on the powder charge, but you always need to work on seating depth, its huge. Also if you want to become more efficient, find your max powder charge, one shot each in .5 grain increments until you hit pressure. Then shoot groups starting and max and working down. Usually the top node is where we end up anyhow.

 

[Sraw]

As always I'm probably the minority however my question is - what's wrong with 41.2 -41.6

I wouldn’t say anything is wrong with it, the impact location on target just isn’t as even as the other groups’.

 

[Sraw]

Looks like your just shooting groups and noting poi and groups size and velocity. Thats good and it what you should do. Thats standard load development. One thing to note on small sample sizes, look at trends. 3 shot groups are plenty for load work. There should be a trend, the groups getting smaller then larger again. If you are not seeing a smooth trend then change a component like powder. Random sized groups that have erratic shapes or poi tell me the powder/bullet/primer combo is wrong. If you had an extremely accurate rifle with the right powder/bullet/primer combo, one shot "groups" would get you real close just by looking at poi. There is a lot to learn from your groups, poi, shape, size, and the trend. I would say your pretty close on the powder charge, but you always need to work on seating depth, its huge. Also if you want to become more efficient, find your max powder charge, one shot each in .5 grain increments until you hit pressure. Then shoot groups starting and max and working down. Usually the top node is where we end up anyhow.

Based on this data, what would your next couple of steps be?

 

[Alex Wheeler]

42.2 seating depth testing. Your already doing well for a factory barrel so you may not see much improvement.

 

[Alex Wheeler]

As always I'm probably the minority however my question is - what's wrong with 41.2 -41.6

Large poi movement between groups. Small groups in this area most likely wont repeat.

 

[chkunz]

I did not study this in detail so I may have missed something. But I will offer the following:

SD is not meaningful for three data points, take a look at the equation and it will be obvious. You probably need ten or more to get a meaningful SD depending on the variability of your data.

Also there is a lot of variability in three shot groups and they are not worth much, a good one doesn't tell you much and a bad one is more informative.

 

[normmatzen]

Looks like you would be well advised to take your curve of Mv vs load and do a 4th-5th polynomial curve fit with Excel. You may be surprised with the poly curve!

 

[Sraw]

Looks like you would be well advised to take your curve of Mv vs load and do a 4th-5th polynomial curve fit with Excel. You may be surprised with the poly curve!

I have no idea what any of that means.

 

[Sraw]

42.2 seating depth testing. Your already doing well for a factory barrel so you may not see much improvement.

Interesting, not questioning your judgment, genuinely trying to learn here.

Why 42.2 instead of 42.0 or 42.1?

 

[chkunz]

I have no idea what any of that means.

Most people would not know what that means but let me try to explain. Many times you see where there is a straight line drawn thru a plot of data when the data follows close to a straight line. However many times data does not follow a straight line so we look for a curve fit that best follows the shape of the data. Sometimes the best curve to fit the data is more curved than others. A 4th or 5th order curve fit would be a more complex curve fit than say a first order (straight line) or a second order curve fit. This is easy for folks who have had a course in the math at this level but not much help for those who have not had a course in this level of math. However the concept is easy to understand if you have someone to teach you.

You are doing well without this tool so drive on and have fun.

 

[Alex Wheeler]

Interesting, not questioning your judgment, genuinely trying to learn here.

Why 42.2 instead of 42.0 or 42.1?

Its not time to get that picky. Find the best seating depth them come back to powder in finer increments. If your still not satisfied, adjust neck tension and start over. When ever you change something you have to go back and verify other aspects of the load dont need tweaking.