Seating Depth Test

Smoothie25

Member
Joined
Jan 7, 2016
Messages
13
Hi All, I'm working up a load for a new bullet. I found a powder node that had SD 11, ES 21.

Ruger American 243
Sierra Gamechanger 90gr
H4350
Fed 210
Win brass (fired several times in the rifle, trimmed and annealed)

I shot the ladder at 2.26" which is mag length. I used Berger's suggested seating depth test and loaded at 2.22", 2.18" and 2.14". These are my results. Let me know your thoughts on whether or not I'm close or should seat deeper. Should I try another primer?

Also, any idea why my first two shots were nearly touching then 3rd shot is off? I shot three bullets with no break between shots then waited to cool to ambient temp before shooting the next group. It's a sporter barrel so barrel warming up?
 

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Wolf76

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Jan 5, 2014
Messages
902
Location
Grandville, Michigan
40 thousandths are big jumps. I understand its the Berger method.
With C N C bullets, I usually see the sweet spot under 50 thousandths off.
Your horizontal group would cause me to go 5 thousandths longer and shorter for test groups.
 

Tiny Tim

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Jan 26, 2015
Messages
947
What's your "to the lands dimension"? If your already a great distance from the lands at mag length, then all your other distances are even more so. You may already be outside your node at mag length.
 

Smoothie25

Member
Joined
Jan 7, 2016
Messages
13
CBTO to lands is 2.306". Mag length (2.260") is .046" jump. So you think I could have jumped over a good seating depth by using .040" increments?
 

Tiny Tim

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Jan 26, 2015
Messages
947
CBTO to lands is 2.306". Mag length (2.260") is .046" jump. So you think I could have jumped over a good seating depth by using .040" increments?
Its possible. You could try .010-.020 off and single feed. If it is good there, try another bullet. I had a 243 Winchester load with RL22 that had single digit sd and es. Couldn't get it to shoot decent. Used a different bullet and things got remarkably better. YMMV
 

Mikecr

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Aug 10, 2003
Messages
5,776
Location
NC, oceanfront
Most will have multiple nodes where testing PROVES them to be.
Your coarse seating testing showed potential with 2.140.
So at 2.140 go back to your powder (ladder) & redo it. Then with best apparent powder load/node, go back to a finer tweaking of seating about that 2.140. This, for final group shaping only(for tightest).

You might also do a primer swap test.
As long as you have a good powder for the cartridge, things should get a whole lot better than what you have now.
 

Eeegadd

Active Member
Joined
May 12, 2021
Messages
35
Location
Co
Hi All, I'm working up a load for a new bullet. I found a powder node that had SD 11, ES 21.

Ruger American 243
Sierra Gamechanger 90gr
H4350
Fed 210
Win brass (fired several times in the rifle, trimmed and annealed)

I shot the ladder at 2.26" which is mag length. I used Berger's suggested seating depth test and loaded at 2.22", 2.18" and 2.14". These are my results. Let me know your thoughts on whether or not I'm close or should seat deeper. Should I try another primer?

Also, any idea why my first two shots were nearly touching then 3rd shot is off? I shot three bullets with no break between shots then waited to cool to ambient temp before shooting the next group. It's a sporter barrel so barrel warming up?
Start at max length allowed. 5 shots, then increments of .003 deeper. 5 shots each. Look for 2 groups next to each other. Then do 1 more ladder test to make sure.
 

QuietTexan

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Nov 16, 2020
Messages
607
Location
Texas
Just as a reminder, the Berger VLD method is specifically for secant ogive bullets, and is based on moving back from the lands and not mag length.
 

mulie

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Joined
Jul 31, 2009
Messages
73
Location
Colorado
Yuup, 2.14" looks best for powder now. Would run another ladder test starting at .020" closer to the lands. Then in 0.003" increments come back to your 2.14" maybe a couple increments longer; 3 rounds at each seating depth. Clean barrel and shoot fouling shots let barrel cool for a bit prior to beginning your ladder. Shoot your ladder across the rounds at each seating depth randomly. It helps in minimizing the barrel heat, and fouling variation. If you have the ability to shoot a longer distance it may help for better differentiation. It still can be done at 120 yds. Typically Vertical spread is powder and Horizontal spread is bullet seating. After this process depending on how many components for reloads you have you can make a choice and ladder in smaller increments of 0.001" depending on your seating die.
PS you should still look at powder and maybe primer your ES could be better < 10 fps. that will help in determining seating depth.
 
Last edited:

Mikecr

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Aug 10, 2003
Messages
5,776
Location
NC, oceanfront
The Berger test works with every ogive type, and optimum seating is affected by every ogive type to throat combination.
The testing can work with lands a foot from ogives.

Nobody could predict optimum seating for you. It has to be tested for, and you might as well do full seating testing with a coarse round.
Tail chasing here is beginning too narrow in adjustment and overall span. With that, you might never see optimum.

I know people don't like testing, and would rather assume a setting +/- little to nothing.
Just keep in mind that whatever they declare about it, is unlikely to be helpful for the rest of us.
I've watched on forums, for decades, all the declarations/implications that VLDs had to be ITL to shoot. I knew this was not true, because I had actually done full seating testing with them (long before Berger recommended it).
But there still seems no way to steer folks from what they must be reading in gun rags. To understand that seating is significant enough a gain/loss to take seriously.
 
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