Seating depth or charge weight, first?

[garandman]

Several threads brought this question to the fore in my mind again. I'm hearing conflicting views.

Some say find a good seating depth as the way to shrink groups the most, then fine tune via powder charge weight. Tried this and I had terrible results.

Historicall I've always done powder charge first, and fine tuned with seating depth. I had good results doing this - 6.5CM / 338 Norma .

What's the truth, here?

 

[Shinbone]

Relatively new handloader, here, so my processes are still evolving.

For now, I do seating depth for a particular bullet, first. Then move on to trying various powders at various powder weights. No absolutes, but I use this order because seating depth is generally considered *relatively* invariant across different powders.

I then fine tune seating depth once I find a powder and powder weight that looks good.

 

[R.Morehouse]

I start with the charge......

Regards
Rick

 

[JimSC]

pretty much a babe in the woods here compared to most of the posters but I do the Berger seating depth test first at minimum charge, then do load testing looking for flat spots in the velocity curve, then go back and fine tune the seating depth if needed. In step 2 if I don't find a good node I will try a selection of primers.

 

[MikeMcCasland]

I think the answer is that it kind of depends. I've had pretty good success doing it both ways.

A lot of the loading you see discussed here talks about cartridge/bullet/reamer combinations that are somewhat of a known quantity. i.e. a .308 running a 200 hybrid or 200.20x in a ~.170fb chamber, or a .284 running 180s in .220fb etc.

In those instances, it's pretty safe to seat the bullet somewhere in the range where it's 'known to shoot well', and do your powder node first, then go back and fine tune your depth once you've got a charge node. Generally speaking, the rifle is going to shoot well enough for you to easily identify your nodes.

Alternatively, if you're just starting out blind with a factory barrel, an unknown chamber, and some random bullet, you may want to start with a depth test first. Start with a moderate charge weight, and see where it seems to shoot best; then go and run an OCW workup.

I don't think there's any definitive 'right way to do it'...depends on a lot of factors. If pressed for a 'definitive' answer though, I'd say generally speaking I've had the best luck starting them .020" off, and doing an OCW test.

 

[garandman]

.

I don't think there's any definitive 'right way to do it'...depends on a lot of factors. If pressed for a 'definitive' answer though, I'd say generally speaking I've had the best luck starting them .020" off, and doing an OCW test.

That's what has worked for me, in the past. Thanx.

 

[brshtr]

Several threads brought this question to the fore in my mind again. I'm hearing conflicting views.

Some say find a good seating depth as the way to shrink groups the most, then fine tune via powder charge weight. Tried this and I had terrible results.

Historicall I've always done powder charge first, and fine tuned with seating depth. I had good results doing this - 6.5CM / 338 Norma .

What's the truth, here?

As with most things in shooting, this is not a binary true/false type of issue. There are various ways of skinning the cat.

You don’t have to choose one over the other in terms of sequence. You can do both at the same time by shooting a matrix of loads. For example, five seating depths and five powder charges, 25 loads total. At this point, where I’m basically scanning for a tune window, I’ll shoot three-shot groups. You’re looking for a seating depth where several contiguous powder charges have good size and shape and the same elevation on the target. Once you find that depth and range of charges you can fine-tune both in small increments, depending on the accuracy requirements you’re trying to fulfill.

Dave Rabin

 

[urbanrifleman]

By doing the seating depth first with a low charge you can establish a seating depth that will work better at all charges. The seating depth is completely independent of the charge and is the same across all the charges. Whether you do one first or do the other doesn't really matter I suppose but the understanding that the seating depth is an absolute and is by far the most influential Factor in the case of a non jump tolerant bullet. It is important to know right from the beginning.

Some bullets are very seating depth tolerant.

Some powders have very wide nodes.

I think it is most important to understand the concept then it is to establish an order in which to do it. I think there are a lot of people who still don't believe the seating depth is actually more important then the charge with certain bullets. And that you can never truly be in tune with the wrong seating depth no matter what the charge is. Some people just don't believe this but it's the truth

 

[Fotheringill]

I also do the Berger method first. The results will show the best out of the choices relative to the others. I then refine that down further.

It is a bit perturbing on the charge side of things. You can open the starting and maximum in different manuals and the powder manufacturer's site and see some very wide spreads among the sites and pages. I look at three sources now, two manuals and one powder maker's charges (i.e. Hodgdon). I then take the average starts and maximums, average them and use that average number as a starting point. So far, it has worked for me.

 

[Sniper338]

Another for testing seating first. I measure and do jam, at, 5thou off, 10 thou off, 15 thou off. Then find what its liking/narrow it down... then go to primer testing. A few shots same seating, same powder charge will tell you what primer it likes better, then its onto powder charges... its all just tinkering until you find the sweet spot.

 

[rsmithsr50]

start at the lands, and adjust charge.
at, not jam or in the lands.
this is basically the high pressure point for loads going away from the lands.

 

[Rope2horns]

The correct powder charge will cure a lot of problems....Seating depth test shot at 600yrds by Keith Weil @Cigarcop ...from 10 in to 30 off, most shots would stay in the xring and none would leave the ten ring.....try doing that in a scatter node.
Powder charge first IMO.

 

[Shinbone]

scatter nodes are best avoided, regardless of what causes it.

 

[urbanrifleman]

The correct powder charge will cure a lot of problems....Seating depth test shot at 600yrds by Keith Weil @Cigarcop ...from 10 in to 30 off, most shots would stay in the xring and none would leave the ten ring.....try doing that in a scatter node.
Powder charge first IMO.

Well that is the node for a lot of bullets that are jump tolerant. My Berger 108s don't shoot any different from 20 to 30. I use 25 to be in the middle.

They also shoot small at about 7 into, but not as good, but not horrible in between.

Try that from 20 jam to 40 out and see what you get with say a VLD.

My 6bra with AR Comp barely has scatter nodes. Interestingly enough.

All in all do both. It's a great learning experience to understand how they are actually independent

 

[urbanrifleman]

When I test a new combo I do both in the same day independently.

I make a seating depth test at minimum charge. Repeat twice.

Then do a powder workup at 20 jump until pressure. Twice. Some people use 20 jam but I find that was to spikey.

Next trip you use the best seating depth and bracket a few powder nodes and you should be pretty close after you are done to having found the center of the center of a flat spot.

 

[garandman]

When I test a new combo I do both in the same day independently.

I make a seating depth test at minimum charge. Repeat twice.

Then do a powder workup at 20 jump until pressure. Twice. Some people use 20 jam but I find that was to spikey.

Next trip you use the best seating depth and bracket a few powder nodes and you should be pretty close after you are done to having found the center of the center of a flat spot.

Interesting. Could you es'splain this in less groovy lingo? Berger told me something similar and I wanna make sure I understand "jump" and "jam" and "bracket"... etc...

Why do a seating depth test at minimum... if yer working up powder at 20 thou off?

What am I missing ?

 

[urbanrifleman]

Interesting. Could you es'splain this in less groovy lingo? Berger told me something similar and I wanna make sure I understand "jump" and "jam" and "bracket"... etc...

Why do a seating depth test at minimum... if yer working up powder at 20 thou off?

What am I missing ?

There is some over lap but I dont over think it.

I do +20 to -40 and I chose the numbers between based on the bullet. Most of the bullets I shoot seen to like from +7 to +4, then -15 to -30.

Use three shot groups. I also look for point of impact of nodes. I consider seat depth to have nodes also.

 

[JFrank]

There is some over lap but I dont over think it.

I do +20 to -40 and I chose the numbers between based on the bullet. Most of the bullets I shoot seen to like from +7 to +4, then -15 to -30.

Use three shot groups. I also look for point of impact of nodes. I consider seat depth to have nodes also.

What quadrant are you in

 

[garandman]

I don't mean to be dense and I appreaciate your patience.

My past practice has been to (1) shoot 5-shot groups @ 0.020 off the lands, increasing powder at 0.2 gr increments to find the best size group, starting about middle of the powder range. Then (2) play with seating depth to shrink down that group. Always worked in the past. TIll now.

Now lemme summarize what I think I hear you saying:

1. Find seating depth. Start at minimum charge, starting just tuching the lands increasing jump in .0005 increments. Find the best size group.
2. Find powder charge. At 0.020 off the lands, increase powder at 0.2 gr increments to find powder node.
3. Use that seating depth from # 1, and then fine tune powder charge in smaller increments.

Am I still missing it?

 

[R.Morehouse]

I would think the idea would be to get it done eating the least amount of your barrel as possible. I can chew through a whole lot of barrel life confirming and re-confirming etc.
Do a single shot per charge ladder in the lands up to pressure. Read the holes on the paper and see where your charge window is. Test in there a bit and adjust seating if needed. If you can, do this at your intended distance and see if positive comp. is working for you........Like has been said...." a lot of ways to skin that cat".......

Regards
Rick