Help me finalize my load dev for 6.5CM

[Tripplet918]

Which of the two shot groups would you pick.



The two are the results of expanding my trial of the Satterlee Load Development Technique v2.0. I did 7 different seating depths for the Hornady 140 ELD-M bullet, propelled by 43.1 grains of RL-16. This time from 0.015 to 0.075" from the lands.

The right was seated 0.035" from the lands with 0.19" group, the left is 0.07" from the lands with 0.37" group. The right is a smaller group, the left has half the vertical dispersion.

Im torn between vertical dispersion and group size. Which would you pick?

[Tripplet918]

BTW, my 223 loads didnt have as great results, but the tests were more conclusive.

Rejects - all groups were around 1-2 inches at 100 yards, Hornady 75gr BTHP with 24.7 2520 powder behind it. Except one.





I got a 0.57" group at 0.070" from the lands. I may have to try even deeper seating depths, but half MOA for an 18" AR with a 10x scope is plenty for now.

[kcstott]

Which of the two shot groups would you pick.



The two are the results of expanding my trial of the Satterlee Load Development Technique v2.0. I did 7 different seating depths for the Hornady 140 ELD-M bullet, propelled by 43.1 grains of RL-16. This time from 0.015 to 0.075" from the lands.

The right was seated 0.035" from the lands with 0.19" group, the left is 0.07" from the lands with 0.37" group. The right is a smaller group, the left has half the vertical dispersion.

Im torn between vertical dispersion and group size. Which would you pick?

That's way to large of a seat depth step.

In any even you need to test on each side of each depth to prove which seating depth is the one to use. Group size is not the goal exactly. Group consistency is the goal. If you have a really tight group but it open up if you seat a few thou short or long that's not good. You need a load with a wide window for stability or you will shoot on a hot or cold day or somewhere out of town and wonder why your load ain't working. I will take a larger group that shows consistency with a slightly higher or lower powder charge, or a slightly deeper or shallower seating depth. I don't want a tight group that turns into a shotgun pattern if one minor thing changes.

[Tripplet918]

That's way to large of a seat depth step.

In any even you need to test on each side of each depth to prove which seating depth is the one to use. Group size is not the goal exactly. Group consistency is the goal. If you have a really tight group but it open up if you seat a few thou short or long that's not good. You need a load with a wide window for stability or you will shoot on a hot or cold day or somewhere out of town and wonder why your load ain't working. I will take a larger group that shows consistency with a slightly higher or lower powder charge, or a slightly deeper or shallower seating depth. I don't want a tight group that turns into a shotgun pattern if one minor thing changes.

These are not representative of a step. These are the best that came out of the seating depth tests. I have observed that the groups and vertical dispersion tighten up to these two that I am showing.

Powder charge had been tested and my velocity and groups are stable above and below the powder charged shown here.

From what youre saying, I should test further by doing smaller depth tests than the 1/10,000th that I did, and see if theyre consistently stable?

[LynnJr]

Shoot 5 groups of 5 shots each and pick the group that agg's the best.

[smoothy8500]

I quit shooting groups at 100 and decided on 300yds a long time ago because everything looks the same at 100 yards.

[kcstott]

These are not representative of a step. These are the best that came out of the seating depth tests. I have observed that the groups and vertical dispersion tighten up to these two that I am showing.

Powder charge had been tested and my velocity and groups are stable above and below the powder charged shown here.

From what youre saying, I should test further by doing smaller depth tests than the 1/10,000th that I did, and see if theyre consistently stable?

I'm positive that's a type O. There is no way you're setting seating depth at .0001" steps.
Seating depth should be tested in .002" steps and you typically find a node every .006" give or take.

In any event you need to test a bigger sample size. Testing at longer ranges helps to but you need to factor in wind.

[Tripplet918]

I'm positive that's a type O. There is no way you're setting seating depth at .0001" steps.
Seating depth should be tested in .002" steps and you typically find a node every .006" give or take.

In any event you need to test a bigger sample size. Testing at longer ranges helps to but you need to factor in wind.

Youre right. I meant 0.010 steps.

Previously, I did a charge weight ladder and plotted the velocity. I came upon 43.1 grains as safe, no pressure signs, and fairly plateaud in velocity vs next door neighbor charge weight. I velo node if you will.

I then did the seating depth tests from 0.015 to 0.075 on 0.10 steps, in 3 shot groups.

I came up these two.

I'm gonna load 10 of the 2.225" seating depths and check from grouping and velocity consistency.

[kcstott]

Youre right. I meant 0.010 steps.

Previously, I did a charge weight ladder and plotted the velocity. I came upon 43.1 grains as safe, no pressure signs, and fairly plateaud in velocity vs next door neighbor charge weight. I velo node if you will.

I then did the seating depth tests from 0.015 to 0.075 on 0.10 steps, in 3 shot groups.

I came up these two.

I'm gonna load 10 of the 2.225" seating depths and check from grouping and velocity consistency.

I?d load three to five each in .002? steps above and below the group that is the tightest. Reason being, you are on the edge of spiting a round. Left group has two holes as opposed to the single hole on the right. I?d also reduce my powder charge 1/10 grain. Are you sorting bullets? And if so how? Base to Ogive or OAL of the bullet? I sort by OAL but I?m also not shooting a bullet with inconsistent Ogives, one reason I stoped using Hornady bullets for anything but mid range or PRS type stuff.
Don?t take that as they are no good. Hornady is fine, they are just not F class quality. Which is what my Daughter and I shoot. That being said you are getting close to the limits of these bullets.
The suggestions made about either a larger sample size or testing at longer ranges will show better results. Longer range is better to show inconsistency in the bullet shape and therefore the BC. That inconsistency most times is too small to show up in a significant way at 100 yards.
In any event .010? seating depth test is a massive step and you may be skipping over the seating mode. How most are finding the node is find the lands then seat .020? deeper. Then work in .002? steps longer, toward the lands. You should see a marked improvement in group size within .015?
That said if you have mag length issues we?ll seat at mag length minus .030? as a max seat .020? shorter than this and work forward as before.
This stuff was a lot more fun when powder was $10 a pound and primers were $15 per K.

[Tripplet918]

^^^Thanks for the insights.

I have all intentions to validate the load with more tests, including truing my ballistic computer. I am trying to get to a load using the Satterlee method first. I am a little unclear on how to finalize the load from the videos and articles Ive read.

[kcstott]

^^^Thanks for the insights.

I have all intentions to validate the load with more tests, including truing my ballistic computer. I am trying to get to a load using the Satterlee method first. I am a little unclear on how to finalize the load from the videos and articles Ive read.

It's real simple.

From start to finish
Velocity test your 10 or fifteen rounds in .2-.3gr steps at .020" off the lands. Find the flat spot.
Velocity test three to five rounds of a centered powder charge and three to five rounds .1gr higher and lower. Shoot these in a round robin. Meaning shoot 1 round each at a different target working from low to high. This reduces influence from shooter fatigue and barrel heat. Confirm low ES and SD. We want a SD of 10 or lower. Note we are not shooting groups yet.

Now you should have a load with a SD=/<10 and now you can start your seating depth test and start shooting groups.
.020" off lands and work forward as mentioned in .002" Do not settle on a perfectly flat group. Settle on one that looks as close to tight little clover leaves with tight groups at a step longer and shorter in seating depth. This is a stable and consistent load.

If you really want to dial it in you load the new seating depth and load five shots groups in 0.1gr increments 0.5gr on each side of your node. (if pressure is not an issue and the load is safe) this will cover an entire grain of powder and you will be able to pinpoint where the powder node starts and ends. in the summer load toward the lower side of the node and in winter load toward the higher side.

If you have a barrel tuner now is the time to tuner test.

My rules of thumb passed down from the US rifle team.
Find stable combustion first. i.e. low SD's
Seating depth for smallest group.
Tuner testing if you have it.

Low SD means you have good combustion
Small clover leaf means good harmonics.
If you have a good group at 100 yards but it's much larger in MOA at long range that's external ballistics and you need to look at your bullet.
It's not hard but we loose focus on the goal and it's real easy to get to deep in the minutia. don't go down the rabbit hole. just stay focused.