Starting Seating Depth

[RDK]

I have gotten multiple answers to this one so I wanted to ask what ya'll thought. I have asked the question when starting a ladder development, where do you start on seating depth? I have gotten answers of 0.015-0.02 off the lands which works great for long bullets link on my 6.5 CM, but now I am working on a load for my 30-06. There is the desire to load from the magazine, so there's a constraint but 0.015 off the lands still cycles but doesn't put much bullet in the case. I have been told to make sure that one caliber worth of bullet is in the case, then there is the recommended depth from the reloading manual, and finally I have read a couple of articles, one by Berger that says choose seating depth first by loading a mid-powder charge adjusting depth by 0.030-0.040 to find what shoots best before even starting a ladder. They state at least in their VLD bullets that seating depth accuracy nodes are .030 to .040 wide. The article is at https://bergerbullets.com/vld-making-shoot/. So you might sense my curiosity and frustration since I am getting different pieces of advice. I'm trying to tune in on the most efficient method for load development esp. with the present scarcity. So where do you all start with seating depth and do you find it to be true that your gun likes the same seating depth to lands regardless of bullet? In other words, how do you zero in on seating depth as quickly and efficiently as possible? BTW, I intend for all my guns to be used in hunting so staying off the lands is a given. Thanks a bunch.

 

[JFrank]

If you start with a tangent ogive bullet at magazine length you won't need a bunch of rounds as you only move one direction.
Try. maybe 3 rounds each at .005 increments

 

[AJC1]

Start at mag length and move back in increments. I use 5 round test groups. More is always better than less. Stop at minimum sami oal or when the ojive leaves a gap at the case neck which ever you get first.

 

[CoalCrackerAl]

I seat to where i can crimp on the cannelure. If no cannelure. I go by the data C.O.A.L.

 

[Ifishsum]

For most hunting bullets I start with at least a caliber's worth of bullet shank in the case, is at least .015-.020 off the lands and fits in the magazine - whichever produces the shortest OAL. Then test for a powder charge that works. If that doesn't produce acceptable accuracy I usually just try a different bullet or powder combination, because I've not often found that changing seating depth makes a significant difference at that point. If a load shows promise I may try a few steps shorter to fine tune.

 

[RDK]

If you start with a tangent ogive bullet at magazine length you won't need a bunch of rounds as you only move one direction.
Try. maybe 3 rounds each at .005 increments

At what powder? MIdpoint?

 

[RDK]

Start at mag length and move back in increments. I use 5 round test groups. More is always better than less. Stop at minimum sami oal or when the ojive leaves a gap at the case neck which ever you get first.

What powder charge, midrange?

 

[JFrank]

At what powder? MIdpoint?

I do a little research first and hopefully have a pretty good idea where the node will be so an abbreviated charge test saves barrel life.
Much the same as seating I stay with about 3 rounds each increment until my course adjustments tell me what I want to hear/see my thinking is that if three shots look bad why shoot 4 or more? YMMV

On a side note I have a couple threads posted somewhere on quick tuning a 270wsm that may give some further information.

 

[NMexJim]

There are several approaches to developing a load. All require a chronograph. My approach is:

• Carefully prepare my brass. For high precision, I use Lapua or Hornady if I can't get Lapua. To avoid neck turning, I don't use anything else.
• I will research and choose my powder using as many sources as I can. The powder I choose should nearly fill the case. At least 75% or even 80%. This is called powder density.
• I won't be too concerned with accuracy and will concentrate on finding a powder charge first, and so will seat all bullets .030 off the lands. The distance isn't too important just as long as it's not in the lands or very close to them.
• I load by three of a powder in 2 grain increments from mid-level load up to max loading. This should not require a bunch of loads. Most accuracy loads will be found in the higher velocity/pressure range. Watch for pressure signs in the very upper level. Bolt lift get harder, case head is expanded.
• Fire each group over the chrono. You really don't even have to use a target, but use them - you might get lucky. Take your data home and graph it out. We're looking for several loads that all show about the same velocity on the chrono. A flat spot in the graph. On the ladder.
• Start reloading by seating depth using the powder and load you've found. If you're using something like a Berger, look at what they suggest. I don't jam other than to find out what jam depth is so I can back off.

Others jump in and add please.
Good luck.

 

[AJC1]

What powder charge, midrange?

I do OCW testing first, some will do seating depth first... I run ocw at mag length or .020 off then test seating depth. They both need to be done and you have one factor to guess while the other is roughly tested.

 

[Blue68f100]

I normally use what the mfg suggest in the load data book, aka bullet mfg. The bullet mfg has a good idea on what will work best with their round. After I have found my sweet spot in the load I will then run a OAL test followed with a primer test. The OAL test will normally use to tighten the group. Where the primer test is used to find what works best on paper and SD's if shooting long range.

 

[FROGO207]

I agree. A propellant charge will make a much bigger difference in accuracy and bullet depth is a fine tuning if you will. A lot of times if you scour the net you will come up with several people that have the same load/length and that is accurate. I use that length and work up to the same charge and look for accuracy. This has saved me lots of components over the years when finding accuracy.