Seating Depth

[bluedog69]

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

So could you give a quick run down on 30 rounds? Do you do 3 shots at a given powder charge then jump it up 1/10th or 3/10's of a grain?
Thanks ahead of time.

 

[Rick Richard]

I load near max recommended powder charge, find the beginning of pressure, back off some and then find most accurate charge. All this done with projectile about .030 OTL. I then play with seating depth which normally doesn't change much. I can do this way less than 30 rounds as mentioned in a previous post. Just the way that has worked for me for a bunch of years…I ain't changing.

 

[Moondoggie]

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.

Yeah, what he said ^

 

[Willys]

Seating depth test before ladder test so your powder ladder will have a chance to be meaningful. After settling on powder load go .005 each side and see if it shoots tighter.

 

[Jeffpatton00]

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.

Mikecr, you say " to find worst result." I'd have thought you'd start with the best result, can you explain the mechanics of starting with the worst result? thx.

 

[Mikecr]

Good point Willys. If you do ladder testing with worst seating, good luck figuring anything out of it.
Seating is not tuning. It's prerequisite to tuning (like best primer).

 

[Beluebow]

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.

Maybe...

Powder charge then seating depth......seating depth is a means to fine tune the powder charge. If the powder charge is in a scatter node no amount of seating depth changes will shrink that. With todays hybrid style bullets seating depth is an easy workaround IMO.

 

[bluedog69]

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.

So if I am reading this right you pick the crappiest powder load group at 10 thousandths off the lands.
Then you start seating depth testing with this crappy powder load group?
Then you stick with that coarse seating depth and do powder charge testing?
Then do tweaking on fine seating depth?

 

[Culpeper]

I've gotten lazy over the years but seating is key. To be brief, I use the barrel length optimal time formula. Reconcile that to QL. Run up 20 loads in .3 increments to find a node. Then seating tests for accuracy on that note. This generally will get me on the bench sub moa pretty quick. The only problem is this will produce a MV that is a little slower as the next fastest barrel time results in MV that is slightly too high for QL. But the results are surprisingly accurate on target, all things considered. I'm satisfied with .75 moa but usually can get below .5 moa. Seating depth test is from jammed to .02. long skinny high BC bullets may need more. That is just me using a lazy hybrid load work up.

 

[Mikecr]

Mikecr, you say " to find worst result." I'd have thought you'd start with the best result, can you explain the mechanics of starting with the worst result? thx.

What I'm looking for is a charge that is furthest from a powder node.
Seating changes pressure, but while away from lands the pressure change is not much. So if you can get between powder nodes, you should be well clear of them during seating testing.

Ideally you would achieve ugly grouping that opens & closes ~1/2moa(or more) with seating changes.
This way you know for sure when you've hit on seating that provides the best bullet-bore interface. There is nothing else causing this apparent condition.
You need to go into this with an understanding that you're not tuning. You're optimizing seating. That's all.

 

[Mikecr]

So if I am reading this right you pick the crappiest powder load group at 10 thousandths off the lands.
Then you start seating depth testing with this crappy powder load group?
Then you stick with that coarse seating depth and do powder charge testing?
Then do tweaking on fine seating depth?

Yes, that's right.

 

[Beluebow]

What I'm looking for is a charge that is furthest from a powder node.
Seating changes pressure, but while away from lands the pressure change is not much. So if you can get between powder nodes, you should be well clear of them during seating testing.

Ideally you would achieve ugly grouping that opens & closes ~1/2moa(or more) with seating changes.
This way you know for sure when you've hit on seating that provides the best bullet-bore interface. There is nothing else causing this apparent condition.
You need to go into this with an understanding that you're not tuning. You're optimizing seating. That's all.

That is about as bassackwards as it gets right there. Looking for the worst load to start load development is a waste of components. I feel sorry for any new shooters that read this and take it as gospel.

 

[Culpeper]

I load near max recommended powder charge, find the beginning of pressure, back off some and then find most accurate charge. All this done with projectile about .030 OTL. I then play with seating depth which normally doesn't change much. I can do this way less than 30 rounds as mentioned in a previous post. Just the way that has worked for me for a bunch of years…I ain't changing.

That is old school. When I was young the old timers taught me me to find the max then back of .5 grains and test for seating and call it. No fooling around. Get it done. It works. These guys could shoot.

 

[Monteria]

I didn't post specifics originally because I super simplified the instructions Mike originally gave me... It works but, someone looking for more precision might want to follow Mike's instructions much more closely.

I start running what-ifs in QL. I pick a low pressure load with a charge that I think will be well outside of any node. If I have powder that I want to get rid of, I'll use that. Basically I throw a dart at the board and hope for a poor result.

I find my max OAL (to the lands-10thou, at least one bullet diam seating depth, or max mag length, which ever is shortest or makes most sense for application)

I load 3 rounds each at max length, max-30, max-60, max-90, max-120. (Yes, I do that big a range because what I want for my purpose is the widest, most stable seating window.)

Take the best group (smallest with bias for least horizontal spread. Though I may have made that horizontal part up in my head, it makes sense to me)

Back to QL, I take the powder I want to use and find theoretical max load.

I then load chosen seating depth with max load-1.5gr, max load-1gr, max load-.5gr, max load and max load+.5gr.

The target I posted previously is chosen seating depth and theoretical max load-.5gr.

If it's garbage, another bullet or another powder is in order. I'll usually go another powder first because I usually want to stick with my chosen bullet.

If I wanted to further refine at this point, I would fine tune seating depth, then charge weight, in the exact same way but with smaller increments on both sides of my best load from above.

Steve