Next seating depth to try?

[OmegaRed]

Did a ladder with my 6BR at 500yds and determined my node was between 30.1 and 31 grains of RL15.

Last night I started with seating depths of these 4 charges at .020 jam, .015 jam and .010 jump, hoping I'd get lucky wit one if these before more testing. No real standout groups, but one was potentially promising ( 31gr @ .020 jam). This group that measured .4 horizontal, but only 003 vertical. This load also put me in the sweet spot of about 2900fps.

From what I've read this means neck tension or fiddling with seating depth in smaller increments..

I'm thinking of doing .017 jam, .023 jam and reshooting the .020 jam. Thoughts or ideas on where to go from here?

 

[Keith Glasscock]

Looking at those targets, and assuming that they were shot at 100 or 200 yards, you might be better served by starting at .020 jam and working backward (toward jump) in .003 increments.I would also focus on the middle of the charge window that you have. You will find a couple of sweet spots along the way. Once you have those figured out, proof them by shooting groups with + and - charges at each identified seating depth. The winner will be the one that stays together and keeps grouping even with velocity changes.

Be sure to do your testing with wind flags. It can take a lot of the frustration out of the job.

 

[mikecr]

I think you're wasting barrel life with that approach, and unlikely to find actual best seating with it.
Do yourself a favor and carefully read over Berger's recommended seating testing.

 

[savageshooter86]

Did a ladder with my 6BR at 500yds and determined my node was between 30.1 and 31 grains of RL15.

Last night I started with seating depths of these 4 charges at .020 jam, .015 jam and .010 jump, hoping I'd get lucky wit one if these before more testing. No real standout groups, but one was potentially promising ( 31gr @ .020 jam). This group that measured .4 horizontal, but only 003 vertical. This load also put me in the sweet spot of about 2900fps.

From what I've read this means neck tension or fiddling with seating depth in smaller increments..

I'm thinking of doing .017 jam, .023 jam and reshooting the .020 jam. Thoughts or ideas on where to go from here?

Why so much past jam? Most shoot well off of the lands. Jump

 

[HTSmith]

I didn't see what bullet you are using? If it's 105 class, 31 gr of R15 is a lot! I nearly drove myself crazy trying to get "jammed" to shoot. .025" off worked great for me w/ 105VLDH's.

 

[Ned Ludd]

If you're forced to search for a seating depth region that shoots well, loading to seating depth increments that far apart may at least get you to a starting point. However, if you're looking to optimize the load, much finer increments (~.003") within a narrower range will be necessary. If you actually happen to hit upon a good load with seating depth increments that far apart, it's largely luck. Pick a narrower range, tighten up the increments, and look for at least two in a row that shoot equally tight groups. Load to the longest of those, which will give you the most headroom for land erosion before you need to re-do the seating depth optimization.

 

[Tim Singleton]

I believe jam with a certain neck tension is jam seating the bullet longer will only result in the same length when chambered. If your definition of jam is determined by seating the bullet long taking a measurement chambering the round then re measuring again when the bullet is pushed back by the lands this push back dimension is the jam.

 

[Tim Singleton]

This is a good structured method of finding seating depth

http://forum.accurateshooter.com/threads/finding-the-right-seating-depth.3886764/

 

[barefooter56]

Did a ladder with my 6BR at 500yds and determined my node was between 30.1 and 31 grains of RL15.

Last night I started with seating depths of these 4 charges at .020 jam, .015 jam and .010 jump, hoping I'd get lucky wit one if these before more testing. No real standout groups, but one was potentially promising ( 31gr @ .020 jam). This group that measured .4 horizontal, but only 003 vertical. This load also put me in the sweet spot of about 2900fps.

From what I've read this means neck tension or fiddling with seating depth in smaller increments..

I'm thinking of doing .017 jam, .023 jam and reshooting the .020 jam. Thoughts or ideas on where to go from here?

OmegaRed,
Will the 2900 FPS get the job done ( bullet still supersonic at the target) at the range(s) you will be shooting at? That .003 vertical will probably be very hard to improve on especially if the SD ( standard deviation) is 5 or less. You may have all the stars aligned already.
http://bulletin.accurateshooter.com/2016/08/loading-for-long-range-shooting-why-consistency-is-key/
Don't over think this! Rabbit holes can be deep, expensive and fruitless. See attachment.
Take care,

 

[OmegaRed]

Thanks for all the replies. I'll try and address some of the different comments. Seating depth groups were fired at 100 yds.
Cartridge specs:
CCI450's
105 VLD Target
RL15
Lapua Cases


While doing pressure testing, I worked up from 27.5 to 31.5 grains of RL15. Even at 31.5, there were no signs of pressure. From the reading that I had done, that sounded a bit high, but have to use the data/gun in front of me as the rule...

My ladder test shot at 500 yds:
7/31/2016

77 degrees 83 degrees
Round 1 Round 2
29.5 2777 2783
29.8 2801 2818
30.1 2807 2842
30.4 2836 2879
30.7 2861 2904
31.0 2879 2923
31.3 2930 2956

30.4 and 30.7 grouped the closest, followed by 31. and 31.3. The first round exhibited the same

Which moves me to my next point. Should I just pick a middle point of powder charge and stick with it? Say 30.5 grains since these grouped well on the ladder test and it's between 2875-2925fps (I read this a few times on accurateshooter in articles, which said this is the range most 6br loads perform the best at)?

It was my understanding that you still had to test the powder charge and the seating depth's in relation to each other. Is this not the case?

There are multiple suggestion on where to go now. Obviously I'm looking for the least amount of wasted components, so should I do:

The Berger recommended bullet seating depths
.010″ into (touching) the lands (jam) 6 rounds
.040″ off the lands (jump) 6 rounds
.080″ off the lands (jump) 6 rounds
.120″ off the lands (jump) 6 rounds

OR

Step down by .003 like some others have suggested?

 

[mikecr]

It was my understanding that you still had to test the powder charge and the seating depth's in relation to each other. Is this not the case?

No, seating and powder are completely different and independent. Read Berger's test carefully. They don't tell you to do seating and powder together, right?
But seating does mess with any particular powder load, so you need to be clear of that.

Pick a powder charge far from any node(which would collapse & skew your judgement of best seating),(two changes at once), and run full coarse seating testing with that. Ideally, your gun would be shooting really bad with an off powder charge, so that you can see grouping opening/closing most purely from seating adjustments alone.
Once you have best coarse seating, measure it's CBTO. Your brass should be fire-formed/size cycled to stable dimensions by now.
Then run a ladder(start over with powder), with best coarse seating, to pick a charge.
Do some group shooting, if it sucks, consider your neck tension, primer choice, powder choice, charge choice. Revisit/adjust these(back to ladder) with same bullet and best coarse CBTO.
When grouping is good, perform grouping testing using tiny tweaks of seating to define it's window and shape the grouping. That's all fine adjustments of seating are about.
Log best CBTO, best powder, and all else including seating forces(if you measure this).

All this, barring any issues with your shooting, shooting system, or reloading.
If you've tried everything and still no luck, consider primer striking. You can open & close grouping with adjustments to pin protrusion or spring compression. Hopefully your sear surfaces are not dragging, or the cocking piece isn't hitting or bottoming in the shroud. Watch your bolt handle on firing pin release. If it jumps to adjust open or close rotation, any amount, you should work on that.
If your seating bullet bearing into donut area, or FL sizing of necks, well, you shouldn't.
Bad rest, something weird about bags or their fill? Fix this. No wind flag, hang a ribbon & watch it. Timing shot rate helps.
Many other things.... Bad lens bedding in a new NF NXS cost me pretty bad once, but only because I denied the possibility too long.

From my approach you might also learn that it never made sense to shoot a ladder before at least coarse seating was determined and used. If the seating you happened to pull out of your butt was way wrong, then your shots would be scattering and your interpretations of that would very likely be wrong. Common tail chasing..