6mm Creedmoor Load Development: Powder Charge

[Beetys]

Hi all,

When developing a powder charge for a load, what do you consider to be a "node"?

Is a powder charge node specific to ES and SD, or it relative to accuracy?

I'm starting to narrow down between a few different powder charges; Here is the relevant data i collected today to provide a point of reference. I've already tested seating depth, and found a node at 2.192 CBTO (sub 0.375 in groups across 2.189, 2.192, and 2.195).

6 mm Creedmoor
Powder: H4350
Primer: CCI 450
Case: Lapua
Bullet: Berger 105 gr Hybrid Target

Chronograph: Magnetospeed Sporter attached to Barrell while testing. I've never noticed a tremendous difference in group size attached vs unattached, but taking this into consideration.

40.0 gr (5 shots)
MV: 62 ES, 22 SD (Obviously horrendous)
Group size: 0.412

40.5 gr (5 shots)
MV: 8 ES, 3 SD
Group size: 0.252

41.0 gr - ES, SD & Group size opened up badly. I'm sure I can probably do further testing around 40.5 to confirm accuracy, and MV. I jumped from 40.0 to 40.5, to 41. I only started incrementing by 0.1 when I reached 41. Maybe a mistake?? How many rounds are you guys going through while developing a load?

42.0, 42.1, and 42.2:
Group size with 42.0 was 0.397, but with 42.1 and 42.2, opened up to 0.916 and 0.832 respectfully. However, my MV was most consistent with these three charges. 42.0: 6 ES, 2 SD, 42.1: 7 ES, 3 SD, 42.2: 11 ES, 5 SD.

My thought process is to further test around 40.5 gr - perhaps test 40.4, 40.5, and 40.6. Any thoughts?

https://imgur.com/a/rKy0pWF

 

[rijndael]

You don't have enough chrono data with only 5 shots per test to say it's good or bad. It's statistically insignificant. I have 20 shot chrono strings where the first 5 shots had amazing SDs but opened up a lot over the remaining 15 rounds.

 

[Beetys]

You don't have enough chrono data with only 5 shots per test to say it's good or bad. It's statistically insignificant. I have 20 shot chrono strings where the first 5 shots had amazing SDs but opened up a lot over the remaining 15 rounds.

So you're proposing that I should shoot 20 shot groups across 10 + different loads to find a good load?

 

[rijndael]

I'm saying 5 shot chrono data is practically worthless. Here are 6 consecutive shots for a load:

2578
2581
2584
2584
2581
2580

The SD of that group is about 2.

When I shoot a 20, the SD is 15 and the ES is almost 50. Checking only those 6 shots, shot consecutively, you'd think it's great. It's not.

 

[Goodcat]

So you're proposing that I should shoot 20 shot groups across 10 + different loads to find a good load?

I disagree with him. IF your loading fundamentals and your dies are good. I anneal after every firing, bushing FL size, then open up the neck to 1-1.5 thou neck tension with a mandrel. I shoot one load per charge weight in 0.3gr increments and develope an excel graph. Easy to see your nodes. Find the flat point at top or bottom nodes and load in 0.1gr increments around them. Then check seating depth after. If my SD is similar in both nodes, I go for the faster if no pressure signs. Easy to find the node with 1 shot each charge, though many average over 3 per charge. Always turns out the same for me. This is assuming you are using a reliable chrono like a magneto speed or Labradar.

 

[Goodcat]

I'm saying 5 shot chrono data is practically worthless. Here are 6 consecutive shots for a load:

2578
2581
2584
2584
2581
2580

The SD of that group is about 2.

When I shoot a 20, the SD is 15 and the ES is almost 50. Checking only those 6 shots, shot consecutively, you'd think it's great. It's not.

what chrono are you using?

 

[rijndael]

what chrono are you using?

Magnetospeed.

 

[Goodcat]

Magnetospeed.

Awesome. What is your method of load development concerning velocity nodes, rounds per charge, etc?

 

[jepp2]

Any thoughts?

Lots of thoughts. To begin with, I don't have a good understanding of your rifle/scope capability, your rest, and your shooting ability (don't take this personally).

42.1 gr is stringing horizontally, 42.2 gr is stringing vertically, A 0.1 gr change in powder shouldn't cause that change. Was the barrel getting hot on the 42.2 gr load which may have resulted in vertical stringing.

I can't say I ever see good correlation between low ES & SD and being on a node, or at a load that give the best accuracy. That said, my ES & SD in a 223 ctg is normally not very good, but in a 6 CM is excellent. I used to use QuickLoad on everything. But more recently I have begun using GRT (free download) and find the powder adjustment for nodes is far superior and working well for me.

You have picked one of the two best powders I use with my 6 CM loads, and good choice on brass and bullets. I don't tend to use the 450 primers, but will try everything I have given certain situations.

I mostly shoot 3 shot groups. They can tell me what will not shoot, but it takes more shots to tell me what will shoot. But I can enter the velocities into GRT and it will give the adjustments for my nodes.

I really don't want to do load development with something hanging off the end of my barrel. May not know what I am missing, so Magneto Speed users don't flame me.

How many rounds down your barrel. Has it finished speeding up yet? When was your barrel last cleaned? Your first group if shot after cleaning, will exhibit more variability until you get it fouled. Just so much I don't know about your setup like I mentioned.

This is a great forum, and most will have more experience than I do.

 

[Goodcat]

Lots of thoughts. To begin with, I don't have a good understanding of your rifle/scope capability, your rest, and your shooting ability (don't take this personally).

42.1 gr is stringing horizontally, 42.2 gr is stringing vertically, A 0.1 gr change in powder shouldn't cause that change. Was the barrel getting hot on the 42.2 gr load which may have resulted in vertical stringing.

I can't say I ever see good correlation between low ES & SD and being on a node, or at a load that give the best accuracy. That said, my ES & SD in a 223 ctg is normally not very good, but in a 6 CM is excellent. I used to use QuickLoad on everything. But more recently I have begun using GRT (free download) and find the powder adjustment for nodes is far superior and working well for me.

You have picked one of the two best powders I use with my 6 CM loads, and good choice on brass and bullets. I don't tend to use the 450 primers, but will try everything I have given certain situations.

I mostly shoot 3 shot groups. They can tell me what will not shoot, but it takes more shots to tell me what will shoot. But I can enter the velocities into GRT and it will give the adjustments for my nodes.

I really don't want to do load development with something hanging off the end of my barrel. May not know what I am missing, so Magneto Speed users don't flame me.

How many rounds down your barrel. Has it finished speeding up yet? When was your barrel last cleaned? Your first group if shot after cleaning, will exhibit more variability until you get it fouled. Just so much I don't know about your setup like I mentioned.

This is a great forum, and most will have more experience than I do.

The magneto speed will change your POI, but won’t change velocity. Good if you like to use graphs, I do. But it affects barrel harmonics slightly like a tuner, so if shooting and reading groups only, I think Labradar is superior. I develop my loads at 200 and only concentrate on SD until seating depth time and have never had an issue at 1,000 to 1-mile developing something on SD, though mileage may vary with everything that can happen over those distances.

 

[rijndael]

I really don't want to do load development with something hanging off the end of my barrel. May not know what I am missing, so Magneto Speed users don't flame me.

Me neither, so no flaming from me. I use an MK Machining Arca Mount and I use Tubb's suggestions of a 2cm'ish gap from the bayonet to bore, and set the sensitivity to 8. With this method, it has no impact on the POI - at least for me.

 

[rijndael]

Awesome. What is your method of load development concerning velocity nodes, rounds per charge, etc?

I can try to write something out tomorrow, but I'm turning in for today.

 

[Goodcat]

Me neither, so no flaming from me. I use an MK Machining Arca Mount and I use Tubb's suggestions of a 2cm'ish gap from the bayonet to bore, and set the sensitivity to 8. With this method, it has no impact on the POI - at least for me.

I really need to give that a shot.

 

[JFrank]

Hi all,

When developing a powder charge for a load, what do you consider to be a "node"?

Is a powder charge node specific to ES and SD, or it relative to accuracy?

I'm starting to narrow down between a few different powder charges; Here is the relevant data i collected today to provide a point of reference. I've already tested seating depth, and found a node at 2.192 CBTO (sub 0.375 in groups across 2.189, 2.192, and 2.195).

6 mm Creedmoor
Powder: H4350
Primer: CCI 450
Case: Lapua
Bullet: Berger 105 gr Hybrid Target

Chronograph: Magnetospeed Sporter attached to Barrell while testing. I've never noticed a tremendous difference in group size attached vs unattached, but taking this into consideration.

40.0 gr (5 shots)
MV: 62 ES, 22 SD (Obviously horrendous)
Group size: 0.412

40.5 gr (5 shots)
MV: 8 ES, 3 SD
Group size: 0.252

41.0 gr - ES, SD & Group size opened up badly. I'm sure I can probably do further testing around 40.5 to confirm accuracy, and MV. I jumped from 40.0 to 40.5, to 41. I only started incrementing by 0.1 when I reached 41. Maybe a mistake?? How many rounds are you guys going through while developing a load?

42.0, 42.1, and 42.2:
Group size with 42.0 was 0.397, but with 42.1 and 42.2, opened up to 0.916 and 0.832 respectfully. However, my MV was most consistent with these three charges. 42.0: 6 ES, 2 SD, 42.1: 7 ES, 3 SD, 42.2: 11 ES, 5 SD.

My thought process is to further test around 40.5 gr - perhaps test 40.4, 40.5, and 40.6. Any thoughts?

https://imgur.com/a/rKy0pWF

I would review charges on each side of 40.5 in .1 gr increments, the 42.0-42-2 load appears unstable and shifting. Did you use wind flags ?

 

[Beetys]

I really need to give that a shot.

lol

I would review charges on each side of 40.5 in .1 gr increments, the 42.0-42-2 load appears unstable and shifting. Did you use wind flags ?

That's what I was planning on.

It was 15 + MPH winds today from 3 o clock.

I also tested many other loads, and noticed that the hotter loads favored high and left while using my magneto speed. From like 41.5 - 42.2 in 0.1 gr increments, this was consistent.

When Goodcat mentioned the magneto speed can affect harmonics, can this be exacerbated while in a 15+ MPH wind? If the magento speed is being blown in the wind, can that have an affect on the harmonics? It didn't seem to impact MV considering that i had solid ES and SD across many loads.

EDIT - To clarify, what would you expect to impact POI more? The wind on the projectile for a 100 yard shot or the wind on the magneto speed as it relates to harmonics?

The magneto speed will change your POI, but won’t change velocity. Good if you like to use graphs, I do. But it affects barrel harmonics slightly like a tuner, so if shooting and reading groups only, I think Labradar is superior. I develop my loads at 200 and only concentrate on SD until seating depth time and have never had an issue at 1,000 to 1-mile developing something on SD, though mileage may vary with everything that can happen over those distances.

^^^^^^^^^

 

[JFrank]

lol



That's what I was planning on.

It was 15 + MPH winds today from 3 o clock.

I also tested many other loads, and noticed that the hotter loads favored high and left while using my magneto speed. From like 41.5 - 42.2 in 0.1 gr increments, this was consistent.

When Goodcat mentioned the magneto speed can affect harmonics, can this be exacerbated while in a 15+ MPH wind? If the magento speed is being blown in the wind, can that have an affect on the harmonics? It didn't seem to impact MV considering that i had solid ES and SD across many loads.

EDIT - To clarify, what would you expect to impact POI more? The wind on the projectile for a 100 yard shot or the wind on the magneto speed as it relates to harmonics?



^^^^^^^^^

If you feel the wind skewed your test then you may need to test again. We need good data to make good decisions.
I have a particular interest in this caliber so I hope y’all don’t mind me trolling the thread.
Thx

 

[Goodcat]

lol



That's what I was planning on.

It was 15 + MPH winds today from 3 o clock.

I also tested many other loads, and noticed that the hotter loads favored high and left while using my magneto speed. From like 41.5 - 42.2 in 0.1 gr increments, this was consistent.

When Goodcat mentioned the magneto speed can affect harmonics, can this be exacerbated while in a 15+ MPH wind? If the magento speed is being blown in the wind, can that have an affect on the harmonics? It didn't seem to impact MV considering that i had solid ES and SD across many loads.

EDIT - To clarify, what would you expect to impact POI more? The wind on the projectile for a 100 yard shot or the wind on the magneto speed as it relates to harmonics?



^^^^^^^^^

I would say that wind on a magneto speed won’t affect anything, the weight at the end of the barrel may affect harmonics slightly, if any. A full value wind at 10mph at 100 yards would be around 1.25” max for your load. But consistent wind doesn’t change groups. Edit: sorry just saw win speed. 2.6” max, but again if the wind was consistent or you weren’t in a tunnel of berms.

 

[Beetys]

If you feel the wind skewed your test then you may need to test again. We need good data to make good decisions.

I would say that wind on a magneto speed won’t affect anything, the weight at the end of the barrel may affect harmonics slightly, if any. A full value wind at 10mph at 100 yards would be around 1.25” max for your load. But consistent wind doesn’t change groups.

I'm going to test again at 40.3, 40.4, 40.5, 40.6, and 40.7 to confirm.

Here are 3, 3 shot groups when testing seating depth. The "X" are not my shots.

I was testing with a 40.0 powder charge.

Today, 40 gr did not meet my goals with ES and SD, but 40.5 did. 40.5 also was shot at a .25 in group across 5 shots, and 40 gr was shot at a 0.41 inch group across 5 shots. Last week, 40 gr was shot at a 0.359 in group across only 3 shots. It's consistent. EDIT - It's consistent for my skill level I should say. I'm sure this is a large deviation for some of you guys.

At the end of the day, the only thing i care about right now is repeatability. In total, I went through 200 rounds to develop a load. To me, that seems excessive, but maybe thats standard?

https://imgur.com/a/cl2SyhT

 

[Goodcat]

I'm going to test again at 40.3, 40.4, 40.5, 40.6, and 40.7 to confirm.

Here are 3, 3 shot groups when testing seating depth. The "X" are not my shots.

I was testing with a 40.0 powder charge.

Today, 40 gr did not meet my goals with ES and SD, but 40.5 did. 40.5 also was shot at a .25 in group across 5 shots, and 40 gr was shot at a 0.41 inch group across 5 shots. Last week, 40 gr was shot at a 0.359 in group across only 3 shots. It's consistent.

At the end of the day, the only thing i care about right now is repeatability. In total, I went through 200 rounds to develop a load. To me, that seems excessive, but maybe thats standard?

https://imgur.com/a/cl2SyhT

I do 10 to find velocity nodes using a chrono, choose my node and do 5 each at +/- 0.1gr from center of node and choose the best SD. I select the higher node if SD is similar. Then I do 3 shot groups at seating depth off the lands with no velocity testing until I see great results, accuracy only. Usually 50 rounds fired max, unless using a barrel tuner next. IMO a good chrono saves you a ton of time. This is after breaking in the barrel.

 

[Beetys]

I do 10 to find velocity nodes using a chrono, choose my node and do 5 each at +/- 0.1gr from center of node and choose the best SD. I select the higher node if SD is similar. Then I do 3 shot groups at seating depth off the lands with no velocity testing until I see great results, accuracy only. Usually 50 rounds fired max, unless using a barrel tuner next. IMO a good chrono saves you a ton of time. This is after breaking in the barrel.

Could you give me an example of your 10 to find a velocity node?

How many grains wide is a velocity node? Roughly 0.3 gr?

I really appreciate your feedback. I don't know why I assumed starting with seating depth testing came before powder charge, sequentially.

Going forward, this is what i'll be doing.

When your testing powder charge, are you just seating 0.02 off the lands as a standard?