Ranking loading variables to lower ES and SD

[Dusty Stevens]

More powder is usually the answer but i think between ignition issues and rest setup thats more of an issue than your 30es

 

[WEL]

Lapua small primer brass for one. Optimize your powder charge to make sure you are on a good node. Consistent charge, consistent neck tension, consistent bullet seating depth.

 

[Straightshooter1]

More powder is usually the answer but i think between ignition issues and rest setup thats more of an issue than your 30es

Good point Dusty about "more powder." I meant to mention that in my post as I found in my experience that I get much better chrono numbers and results on paper better with cases at around 100% full. . . . particularly with IMR-4064. Using 38.4 gr of it with the seating dept he's suggesting, it looks like he's only at ~90% of capacity, which I feel could very well be contributing to some extent the numbers he's getting due to ignition issues.

 

[Florida Wally]

Good point Dusty about "more powder." I meant to mention that in my post as I found in my experience that I get much better chrono numbers and results on paper better with cases at around 100% full. . . . particularly with IMR-4064. Using 38.4 gr of it with the seating dept he's suggesting, it looks like he's only at ~90% of capacity, which I feel could very well be contributing to some extent the numbers he's getting due to ignition issues.

I am more than 90%. The cases are not full though. I’ve loaded some loads for testing up to 40 grains based on other comments to this post. At 40 grains they are not compressed, but are pretty full. I’m going to test this weekend.

 

[Dusty Stevens]

I am more than 90%. The cases are not full though. I’ve loaded some loads for testing up to 40 grains based on other comments to this post. At 40 grains they are not compressed, but are pretty full. I’m going to test this weekend.

It doesnt have to be full, its all up to a bunch of factors, but you need a bit more if its vertical

 

[Straightshooter1]

I am more than 90%. The cases are not full though. I’ve loaded some loads for testing up to 40 grains based on other comments to this post. At 40 grains they are not compressed, but are pretty full. I’m going to test this weekend.

Hmmm??? Well, I'd bet it's pretty close to 90%. If you were to load 38.4 grs with a COAL of 2.80, you'd be at 92%. For my 175 SMK's my best load is at 42.0 grs with a COAL of 2.860, which puts me close to almost 101% We're talking about the powder's usable space, not case volume. . . right?

 

[Florida Wally]

Hmmm??? Well, I'd bet it's pretty close to 90%. If you were to load 38.4 grs with a COAL of 2.80, you'd be at 92%. For my 175 SMKdf's my best load it at 42.0 grs with a COAL of 2.860, which puts me close to almost 101% We're talking about the powder's usable space, not case volume. . . right?

COAL is 2.766. I can’t load 42.0 grs without increasing the neck tension. Yes, usable space.

 

[Homerange]

When I do get low ES and SD, vertical reduces to half moa or less. I’m hoping that a consistently lower ES and SD will translate to lower vertical spread. Which of the following variables do you think is/are the most important to reduce ES and SD? I’m trying to figure out what process to more refine next.

1. Powder charge consistency
2. Bullet seating depth consistency
3. Primer
4. Shoulder bump consistency
5. Brass trim length
6. Projectile consistency - bullet sorting
7. Cartridge concentricity
8. Brass volume - sorting
9. Neck tension
10 Neck thickness consistency
11. Other

Thanks in advance!

11 Other
Consisting generally of 4, 5, 7, 8 and 9 and called precision brass prep.

Primer pockets ?
Flash hole chamfering ?

Attention to these details even with quality brass and powder throw consistency should get you right down in ES along with high case fill percentages.

 

[Keith Glasscock]

Tell me about how you did your load development. If you’re just on the edge of a node, no amount of fiddling with little things is going to get it to shoot better, nor hold good ES numbers. It takes a lot of ES to make big groups.

What do you have for a seating depth? Where is that in reference to the lands?

What is the velocity average you are seeing?

Let’s look at this from a wholistic viewpoint...

 

[Florida Wally]

Tell me about how you did your load development. If you’re just on the edge of a node, no amount of fiddling with little things is going to get it to shoot better, nor hold good ES numbers. It takes a lot of ES to make big groups.

What do you have for a seating depth? Where is that in reference to the lands?

What is the velocity average you are seeing?

Let’s look at this from a wholistic viewpoint...

For testing, I use a chronograph to determine the charge and seating depth for accuracy. Average velocity is 2,490 fps. I am seating .027 off the lands. The consensus of the previous posts is to step back and take a more wholistic look at it rather than chase details one by one. I’m going to retest loading with my current regimen and use vertical, not the chrono to find the node for charge. I‘ve loaded to include several increments greater than my current load looking for a node using more powder. I’m concerned about pressure so I’ll stop when I see pressure signs or get above 2,700 fps which will keep me below a calculated pressure of 60,000 psi. Once I find a node with this method, I’ll go from there.

 

[Evan]

For testing, I use a chronograph to determine the charge and seating depth for accuracy. Average velocity is 2,490 fps. I am seating .027 off the lands. The consensus of the previous posts is to step back and take a more wholistic look at it rather than chase details one by one. I’m going to retest loading with my current regimen and use vertical, not the chrono to find the node for charge. I‘ve loaded to include several increments greater than my current load looking for a node using more powder. I’m concerned about pressure so I’ll stop when I see pressure signs or get above 2,700 fps which will keep me below a calculated pressure of 60,000 psi. Once I find a node with this method, I’ll go from there.

I'm interested in hearing how it goes for you!

 

[Ccrider]

Are you getting varying es with the same load? That is what it looks like you are saying. If this is true, the load is going out of tune maybe from day to day, you are doing something inconsistent with your brass prep or your barrel harmonics is changing as it gets dirty.

 

[Florida Wally]

Shot ten 3 shot groups today. It was a little windy early so I set up at 100 yds, but it calmed down to almost no breeze when I shot a warm up group. Tiny bit of sprinkles and overcast. Started testing at 37.2 grs and increased by .3 grs up to 39.9grs. Here are the vertical spreads: 37.2grs - 0.366”, 37.5grs - 0.372”, 37.8grs - 0.306”, 38.1grs - 0.224”, 38.4grs - 0.130”, 38.7grs - 0.087”, 39.0grs - 0.199”, 39.3grs - 0.108”, 39.6grs - 0.162, 39.9grs - 0.712.

Velocities are consistent with previous testing. Looks like the node considering only vertical is from of 38.4 grs up to 39.3grs, with the lowest vertical spread at 38.7grs. I‘m thinking I’ll do seating depth testing next at a selected charge of 38.8grs which I think is in the middle of the node and 0.1 grs from the lowest vertical.

Any thoughts on selecting 38.8grs would be appreciated. Should I retest maybe refining 38.4 to 39.3 with 5 shot groups or am I good to go in the middle?

Thanks for everyone’s help thus far. I feel like I’m turning the corner after a good bit of frustration!

 

[MikeMcCasland]

Looks like you have two nodes identified.

One right around ~37.9gr-38gr, and another at ~39.1gr-39.2gr.

If you were going to re-shoot, I'd load up 5 rounds at both those powder charges, and see what shoots tighter.

Work depth based off that result.

Seems slower than I would have expected, but if it shoots tight...screw it.

 

[JFrank]

At 39.1 i suspect you would have a happy load
once you've completed the seating depth testing even happier..

 

[Florida Wally]

Looks like you have two nodes identified.

One right around ~37.9gr-38gr, and another at ~39.1gr-39.2gr.

If you were going to re-shoot, I'd load up 5 rounds at both those powder charges, and see what shoots tighter.

Work depth based off that result.

Seems slower than I would have expected, but if it shoots tight...screw it.

Thanks Mike. I was looking at the data points incorrectly. I get what you are saying.

 

[Evan]

Thanks Mike. I was looking at the data points incorrectly. I get what you are saying.

I think you've got it already, but I look at the distance between point of impact and point of aim. Looking at your pictures, you can see a nice sine wave showing up. It starts high at 37.9, then drops all the way to 39.0, and then starts climbing again up to 39.6 on the targets. Pretty cool!

EDIT: At greater distance, this becomes more pronounced and you can chart it with more resolution. Out of curiousity, did your previous load put you at the peak, in the middle, or at a trough in the sine wave that you've charted here?

 

[Florida Wally]

I think you've got it already, but I look at the distance between point of impact and point of aim. Looking at your pictures, you can see a nice sine wave showing up. It starts high at 37.9, then drops all the way to 39.0, and then starts climbing again up to 39.6 on the targets. Pretty cool!

EDIT: At greater distance, this becomes more pronounced and you can chart it with more resolution. Out of curiousity, did your previous load put you at the peak, in the middle, or at a trough in the sine wave that you've charted here?

At the peak. I didn’t post since vertical spread was so high, but I wasn’t looking at point of aim vs point of impact. Great observation. This is coming much clearer to me now. You guys know your stuff!

 

[Evan]

There are some theories that the sine wave on target is the bullet leaving the barrel at different times while it's vibrating. If the barrel is on an upswing in its vibration, the bullet goes high. If the barrel is on a downswing then bullet goes low. And as you change your powder charge that changes the pressure and the bullet's time-in-barrel, causing the barrel to vibrate differently. It's a nice idea, even though I am skeptical of it actually happening like that.

 

[Evan]

At the peak. I didn’t post since vertical spread was so high, but I wasn’t looking at point of aim vs point of impact. Great observation. This is coming much clearer to me now. You guys know your stuff!

Also want to add that it looks like you've got a great rifle and are doing a good job of shooting it. Clear results like this are due to the consistency of your shooting!