Seat/charge or charge/seat

[sierracharlie338]

Been doing a lot of pondering lately while working through load development for my 260. Been trying some new things this go-round and am curious what the masses have to say.....

Do you test for seating depth first then a powder charge or do you find the powder charge then chase seating depth?

No wrong answers just want to know what works for you.

SC

 

[Huntsman66]

In no way am I saying my way is right, but I tend to find jam, whether it is limited by the magazine or the chamber and then come back 20k and start powder testing with some fine tuning with seating after that. I use the information from Scott Satterly and Eric Cortina. Has always worked well with fewer components used in the long run.

 

[waspocrew]

Same as above - I usually seat .020" off the lands (if able) and work up the charge from there. Once I find a charge (or charges) that yield the groups I'm looking for, I'll try tuning the seating depth. Seems to work for me!

 

[sierracharlie338]

Same as above - I usually seat .020" off the lands (if able) and work up the charge from there. Once I find a charge (or charges) that yield the groups I'm looking for, I'll try tuning the seating depth. Seems to work for me!

I would categorize yours as charge then seat IMO since 20k off isn't normally the final depth after tuning your depth later. Thanks for the reply.

 

[Huntsman66]

Same as above - I usually seat .020" off the lands (if able) and work up the charge from there. Once I find a charge (or charges) that yield the groups I'm looking for, I'll try tuning the seating depth. Seems to work for me!

I think the only thing I might be doing a little different is I don't necessarily look for groups with the powder, I'm looking for velocity nodes and try to land in the middle of one.

 

[Rick Richard]

I do charge first then seating depth, but start the process .030 off the lands.

 

[QuietTexan]

1. Coarse seating (including picking an arbitrary 0.020" off, mag length, book COL, cannelure decisions in lieu of multiple coarse depths)
2. Charge weight
3. Fine tune seating
4. Neck tension/interference fit/ hoop stress/ etc

Basically I'm saying seating depth has to come first because you have to choose some BTO/COL to run for the charge ladder. So whether or not you TEST multiple depths first, a seating depth decision is always made first. Be it from experience, information, or just blind luck in making a random choice, there's no way to not decide on a seating depth before charge weight.

 

[cdherman]

I like to start as close as possible to the lands, but not jambing. So I aim for .005" off. And then look for nodes with 3 or 4 shot groups spaced up from about 6% below of max load, in .06% (determined variably based on books, quickload, word of mouth or a combination). This way, I think I am getting to max pressure with initial load development. I run the shots over Labradar. Consistency of velocity also helps to find the sweet spot. Once I have the sweet spot, THEN, I seat deeper in increments of 15 or 20 thou to see if I can improve. Since deeper seating results in lower pressure, I don't have to worry about excess pressure later in the load development process. I think of this as a "charge first" process, but I guess QuietTexan has a point that we are ALL pretty much looking at basic BTO seating depth first. But systematically varying the seating depth comes AFTER varying the charge weights.

I just want to get the issue of maximum load and pressure worries over with at the beginning. Seems to me that if you chose some arbitrary charge, say 94% of book max and then varied the seating depth, you would have to worry about pressure signs as you got closer to the lands. So lets say you loaded at 70, 50, 30, and 10 thousand off the lands and determined that your gun likes 30, and then you start to up the charges, you will be looking for pressure signs twice. I hate the suspense of looking at my primers and looking for marred brass and worrying I am over pressure twice....

But this is a very valid question. I'll put it differently: Does optimal seating depth vary with charge, or does the optimal charge vary with seating depth? Which is more? I don't honestly know.

 

[sierracharlie338]

1. Coarse seating (including picking an arbitrary 0.020" off, mag length, book COL, cannelure decisions in lieu of multiple coarse depths)
2. Charge weight
3. Fine tune seating
4. Neck tension/interference fit/ hoop stress/ etc

Basically I'm saying seating depth has to come first because you have to choose some BTO/COL to run for the charge ladder. So whether or not you TEST multiple depths first, a seating depth decision is always made first. Be it from experience, information, or just blind luck in making a random choice, there's no way to not decide on a seating depth before charge weight.

You're splitting hairs. What I am referring to is FINAL seating depth. Of course you have to start somewhere with a seating depth whether it's due to mag length or a dart thrown at a number. Your process is how I normally do it.

 

[FEENIX]

1. Coarse seating (including picking an arbitrary 0.020" off, mag length, book COL, cannelure decisions in lieu of multiple coarse depths)
2. Charge weight
3. Fine tune seating
4. Neck tension/interference fit/ hoop stress/ etc

Basically I'm saying seating depth has to come first because you have to choose some BTO/COL to run for the charge ladder. So whether or not you TEST multiple depths first, a seating depth decision is always made first. Be it from experience, information, or just blind luck in making a random choice, there's no way to not decide on a seating depth before charge weight.

^^^This!^^^ There is no need to complicate it unnecessarily.

 

[Mikecr]

Choosing an arbitrary CBTO to begin is not the same as doing seating testing first.

 

[WildRose]

Been doing a lot of pondering lately while working through load development for my 260. Been trying some new things this go-round and am curious what the masses have to say.....

Do you test for seating depth first then a powder charge or do you find the powder charge then chase seating depth?

No wrong answers just want to know what works for you.

SC

I'll load just short of mag length and ensure they'll feed well.

Work up the most accurate load I can find.

Then adjust seating depth to fine tune.

Saves a whole lot of messing around and burning up precious resources.

 

[WildRose]

Choosing an arbitrary CBTO to begin is not the same as doing seating testing first.

I don't think there's any confusion on that point.

 

[Hard rock]

I don't think there's any confusion on that point.

Maybe if it was worded differently, like what is the final thing you do in load development , powder charge or seating depth.