Seating Depth

[snowcreekkennels]

Im running a mid range powder charge with a seating depth that provides groups of less than a half inch. Will the same seating depth hold true as I increase powder to increase the speed.

 

[Rick Richard]

Some will say yes, but I won't. Whenever you change a variable in your load recipe, more than likely it will effect accuracy. You may have to fine tune again…I would.

 

[LaHunter]

Possibly / Maybe. Only one way to find out for sure. I have a rifle that maintained sub .5 moa (5 shot) accuracy as I increased powder charge by 1 grain (done is multiple steps) while keeping seating depth the same.

 

[Jud96]

Sometimes yes, sometimes no. I start load development doing a quick seating depth test with a starting load and pick the best seating depth from that test. Then I test for powder using the previously best seating depth. Afterwards I will retune seating depth if need be.

 

[Mikecr]

Will the same seating depth hold true as I increase powder to increase the speed.

Yes.
But when you reach your final load you can tweak seating a tiny bit in it's window for tightest group shaping.

 

[Mikecr]

I've found that coarse bullet seating (whether tested best is initially 5thou off or ~40thou off, for example), while huge to results, is independent of powder or charge. Optimum seating is not tuning.
Given this, it makes sense to complete full coarse seating testing before moving into load development. That way it's easier to see the result of your load testing.
But whatever route you choose, don't do full seating testing from a powder node. Pick a charge between powder nodes for seating testing.

 

[sierracharlie338]

But whatever route you choose, don't do full seating testing from a powder node. Pick a charge between powder nodes for seating testing.

Interesting thought here. Now I will have to try this.

 

[Lonewolf74]

Hey Mikecr, would you expand a little on your initial process?

Are you saying essentially that you choose a powder you believe will be good for your application, pick a starting charge weight then test seating depth? Seeing which seating depth is most accurate at a random charge weight?

What sort of graduation do you typically use, ex. touching lands, 20 thou off then 40 thou off etc? Smaller or larger jumps between test rounds?

Always looking for more efficiency in load development!

 

[FEENIX]

Im running a mid range powder charge with a seating depth that provides groups of less than a half inch. Will the same seating depth hold true as I increase powder to increase the speed.

Some will say yes, but I won't. Whenever you change a variable in your load recipe, more than likely it will effect accuracy. You may have to fine tune again…I would.

This!

 

[Stonyman88]

Im running a mid range powder charge with a seating depth that provides groups of less than a half inch. Will the same seating depth hold true as I increase powder to increase the speed.

He's correct , more powder different results, what I've always heard is find the node with different powder charges,then once you find that work on seating depth. I got my 6.5CM to .20 at 200 yds. My node cam in at 39.5 gr of H 4350 but only 2700 FPS, could go up in powder but why.

 

[Wolf76]

There's really 2 main variables that determine the best possible accuracy. Powder charge and seating depth. I've observed that optimal seating depth hasn't changed regardless of powder or powder charge. Seating depth is specific to each bullet sku though.
I determine bullet seating depth first. Then it makes powder and powder charges easy to determine. If half the equation is done, the rest is obvious. For example, if group size doesn't change based on charge, then I'll likely abandon the powder.... unless it's shooting ragged holes
Some go for nodes first and then adjust... I'm just on the other side. Is a zebra white with black stripes or black with white stripes? That's how I see this process.

 

[Stonyman88]

There's really 2 main variables that determine the best possible accuracy. Powder charge and seating depth. I've observed that optimal seating depth hasn't changed regardless of powder or powder charge. Seating depth is specific to each bullet sku though.
I determine bullet seating depth first. Then it makes powder and powder charges easy to determine. If half the equation is done, the rest is obvious. For example, if group size doesn't change based on charge, then I'll likely abandon the powder.... unless it's shooting ragged holes
Some go for nodes first and then adjust... I'm just on the other side. Is a zebra white with black stripes or black with white stripes? That's how I see this process.

Finally somone who knows what's first I think,. lol,,,heard so many opnions on this and really not sure if their white or black either, just going from what some have said, would love to know the best results, I have had good luck with powder charge first but now boing to reverse my load to depth first, see what happens, Please keep me posted, I've found that the Hornady seems to be 50 thou off the lands, when they shoot great. Might have to start at 15 thou and work all the way up and see what happens, Thx Wofl76

There's really 2 main variables that determine the best possible accuracy. Powder charge and seating depth. I've observed that optimal seating depth hasn't changed regardless of powder or powder charge. Seating depth is specific to each bullet sku though.
I determine bullet seating depth first. Then it makes powder and powder charges easy to determine. If half the equation is done, the rest is obvious. For example, if group size doesn't change based on charge, then I'll likely abandon the powder.... unless it's shooting ragged holes
Some go for nodes first and then adjust... I'm just on the other side. Is a zebra white with black stripes or black with white stripes? That's how I see this process

 

[Monteria]

Yes, all changes to all variables will have effect.

The point of Mikecr's method, as I understand it, is to start with tuning the coursest but most stable variable, the one that will have the biggest result with the least likelihood to be negatively effected by other changes, and work to the finer adjustments.

I've adopted his method, probably not to the letter, and I am a convert. My initial load development is now 30 rounds. Depending on the rifle, it's purpose and my expectation, it might stop there. Or, I might go back and do another 30 rounds with finer adjustments... ETC.

Either way, it's given me a very focused method and cut my load development way down with far better results.

The attached is the result of 30 rounds load development and it is stable/repeatable. It's a throw together Remington 700 that no gunsmith has ever touched and most would say shouldnt shoot. Load development started in the 1.25" range. Being a hunting rifle, I stopped there.

Steve

 

[Mikecr]

Hey Mikecr, would you expand a little on your initial process?
Are you saying essentially that you choose a powder you believe will be good for your application, pick a starting charge weight then test seating depth? Seeing which seating depth is most accurate at a random charge weight?
What sort of graduation do you typically use, ex. touching lands, 20 thou off then 40 thou off etc? Smaller or larger jumps between test rounds?

I use a functional variant of Berger recommended full seating testing: https://www.longrangehunting.com/th...-from-berger-vld-bullets-in-your-rifle.40204/

I've found that quality of this testing is contingent on isolation of seating results.
For many guns seating is way larger than powder, but I can't see seating results as well while coming into or out of a powder node.
So after running what-ifs in QuickLoad for an incremental load table, I'll run those charges, 2shts each, with seating at ~10thou OTL, to find worst result. This is the charge I'll run seating testing with, and it's usually with new brass that needs fire forming anyway.
Now I can run wide range coarse seating adjustments without worry of a powder node messing with results.
If you already know upper/lower powder nodes, you can just pick something between them.

For seating I never bother with touching lands. I start 10thou OTL, and 20, 30, 40, etc. 3shts each. Looking for the 1st confirmed group tightening. I'm not going to accept bullet bearing into neck donut area, nor rely on high starting pressure from a close land relationship.
I might horse around with +/-5thou of something on another run, but this is for best coarse seating.
The coarse CBTO I choose is logged, and I do a primer swapping test, and MyMax pressure testing while I'm there.
That's what I'll go back to powder testing with, once my brass is fully fire formed and stable.

After powder testing, I go back to my coarse CBTO and fine tweak it within it's window for tightest group shaping.
Log my final CBTO. I'll never change it for that bullet.