6mm Creedmoor Load Development: Powder Charge

[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.

For a new gun/caliber to me:

Load in 1 grain increments to find signs of pressure.
Back off 4-5%
Bracket 18 shots (6 for each charge) around that 5% reduced charge
Shoot the 18 as (6) 3 shot groups
If things don't look good, I'll slide the charge window up or down.
I note the groups and make sure the fps is where I expect/need it.
Tune seating depth
Shoot 15-20 shots for groups and chrono data for the picked load.
If things look good, I test out neck tension differences.
If things don't look good, I'll work on minor charge differences.

I don't look for the velocity 'flat spot' as I don't believe they exist.

If the caliber is already known to me, I'll just use previous loads and work right around those prior known good ones. I have a pretty big list of loads that tend to work in most guns, like 43 grains of Varget and a 175 SMK.

I've also been known to use GRT. I'll shoot a couple to get charge weight to fps, then work it in there and test. It'll usually put me within a 1 grain window to work in.

Recently I worked up a load for the 175 TMK in my 308 with 4064. I found pressure at 44 grains. I ended up at 41.7. 44 grains - 5% = 41.8. That's also right around a pretty well known good load with a 175 and 308s.

 

[Clancy]

Vertical is not always powder charge. Horizontal is not always seating depth.


You should really leave that chronograph at home until your load development is done.

I test seating first, but you can test powder first if you want, with a bullet at or just into the lands and back up from there.

Half grain jumps in a creed sized case is pretty significant. That’s what I do in magnums. I’d be doing .3 in a creed.

I wouldn’t waste 5 shots on every group. I’d shoot 3 until you find several in a row sharing a common point of impact and similar, round groups.

A “node” in a creed sized case should be at least .6 wide and maybe up to a grain and a half . Find it, load in the middle and be happy.

I’ve been in love with the GT lately and with my bullet and powder I am really solid from 34.5-35.1 grains. I shoot 34.8 most of the time, but they’ll stack as far as I care to shoot within that .6 grain window. That’s a node… you don’t find it with a chronograph unless you’re willing to shoot enough rounds to generate reasonable stats, which would be at least 50, and ain’t nobody got time for that…

 

[Beetys]

Vertical is powder charge, horizontal is seating depth or wind. Google Scott Satterlee load development, and watch all of Erik Cortina’s videos on seating depth. They know a billion times better than me.

Thanks, Will do.

 

[acloco]

Google "modified audette load ladder".

I am in agreement with Clancy. 0.3 gr increments is the right spot for the Creed size case in load development.

Asking questions, is great. In particular, this site has some of, if not THE kind & queens of our love.....accuracy.

Leave the chrono at home. Not needed in load development.

You are trying to find what EACH barrel/bullet/powder/primer combo is preferred by your barrel.

Another hint, shoot at 300 yards. Nodes will be very noticeable. Vertical is velocity. Left to right....well...ahem.....is me.


THE ultimate goal, find out what the barrel likes. Kind of like dating somebody new. Pizza? Steak? Burger? Lobster?

 

[acloco]

PS......StaBall will be your new friend.

 

[Beiruty]

6 & 6.5 Creedmoor Load Data – What The Pros Use

This past year I asked the 173 of the top-ranked precision rifle shooters in the country about the ...

precisionrifleblog.com

 

[Brians356]

We need good data to make good decisions.

Amen. See my signature.
-

 

[barefooter56]

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

With your cross wind and due to its lack of VERTICAL DISPERSION. The target #3 load looks very good.