Charge weight tuning v seating depth tuning

[Tim Singleton]

Full seating testing(Berger recommended) shows totally opposite of this.
Seating is coarse, powder is fine.

I don't know of any BR competitors that would agree seating is coarse

 

[alinwa]

Full seating testing(Berger recommended) shows totally opposite of this.
Seating is coarse, powder is fine.

I can't disagree..... I'm only sharing MY way.

#1...jam-seat some bullets, average and set the seating die, LOCK it
#2...start somewhere safe and work up incrementally to failure, ie find MAX
#3...if see anything promising, play with charge. If not, shoot a sequence trying to find "node" or"nodes"
#4...once a possible node is established, tune from the center of this node using seating depth.
#5...(never works consistently for me but, PUNT) try different neck tensions
#6...(never works consistently for me but, PUNT) try different primers
#7...(never works consistently for me but, PUNT) try the tuna
#8...(never works consistently for me but, PUNT) try another powder

Sometimes nowadays I'll skip all this fooferaww and just try another bullet if I've built the platform for more than one option.

And, mainly, when a gun just SHOOTS HOLES from the get-go, when all's ya got's ta' do is change the SHAPE of the holes.... ya' got a winner.

And if it DON'T???



Most offen YA DON'T....

 

[dmoran]

While both are important, the powder has the most dramatic effects. Individually move both equally 3% incrementally and the results on the targets will be obvious. Even more so by velocity and bullet path/POI.
Once the powder node is zoned in on, seating depth is more critical to accuracy, but up until then, powder charge has the greatest effect, bar none (IME).

 

[jimmymac]

I can't disagree..... I'm only sharing MY way.

#1...jam-seat some bullets, average and set the seating die, LOCK it
#2...start somewhere safe and work up incrementally to failure, ie find MAX
#3...if see anything promising, play with charge. If not, shoot a sequence trying to find "node" or"nodes"
#4...once a possible node is established, tune from the center of this node using seating depth.
#5...(never works consistently for me but, PUNT) try different neck tensions
#6...(never works consistently for me but, PUNT) try different primers
#7...(never works consistently for me but, PUNT) try the tuna
#8...(never works consistently for me but, PUNT) try another powder

Sometimes nowadays I'll skip all this fooferaww and just try another bullet if I've built the platform for more than one option.

And, mainly, when a gun just SHOOTS HOLES from the get-go, when all's ya got's ta' do is change the SHAPE of the holes.... ya' got a winner.

And if it DON'T???



Most offen YA DON'T....

Missed one.

#9...try a different bullet.

 

[jimmymac]

Just 3 shots
Those Barts bt's are pretty amazing

Hey Tim...if you are still shooting that combo where did you actually end up for powder and seating?

 

[Tim Singleton]

Hey Tim...if you are still shooting that combo where did you actually end up for powder and seating?

That barrel went away and I went back to the middle of the pack.
It did win some yard ages and a few SE points before it did
.011 and 28.6 of LT shot well in it that was a good barrel

 

[jimmymac]

Nice. Seems like almost no one runs that mid 28 grain load. 28.6 works good in my old barrel too.

 

[jimmymac]

My bad. I'm running N133. Not sure what the trend is for LT.

 

[Tim Singleton]

i know you can do it Al

What I was trying to show with this pic. Until the seating depth is right they just won't shoot. Put any powder charge in it you like it won't be to it's full potential until the seating depth is right.

 

[rayporter]

what lot of lt was that?
did you ever chrono it?

 

[Tim Singleton]

what lot of lt was that?
did you ever chrono it?

Lot10
3370 or so

 

[mikecr]

I realize that relatively few people do full seating testing to find best seating.
That most competitors just go from what they already know about their load/gun, before ever pulling the trigger on it. Do you think a simple powder workup from jammed -with a seating wiggle inside the lands, would leave you with best from something like a 260AI & 28" barrel?
Maybe. But less likely, and it's not where most find their best.

Full seating testing is way more coarse than powder.
Granted, a wiggle inside a seating window is tiny to results. But breach that window and at 1kyd you'll have no idea where bullets are going.
Go back to testing at ~300yds, where you can see where bullets are going, and you can easily see that full seating testing changes POI more so than any incremental amount of a given powder.
Seating IS coarse.

You can do your sinewave down to single kernels of powder, and thousanths of actual tension. These are fine adjustments.

 

[dmoran]

@mikecr
If seating is so much more coarse, how is it that I can keep all shots on a 48" target at 1000yds to cover from 020-In to 100-Off, but for powder be lucky to get 5% change in charge increments to stay on?
And obvious how worse vertical dispersion can be on powder scatter nodes then from seating scatters at distance.

 

[dmoran]

@mikecr
Examples for you:

1st is a 1-grain powder ladder test in 2-tenth increments (2-shots at each increment) that accounts for +1.5-MOA of vertical dispersion, from a rifle and load combo that is capable of 0.3-MOA groups on the node:




Next a 3-grain increment ladder test with vertical references that accounts for +4-MOA of vertical dispersion in total. Notice how even 0.3-tenths variation in charge can easily account for +1-MOA of vertical dispersion.

​

Next is .005" increments of seating. 8" of vertical being the worse of the 5 increments. 1-MOA total vertical to all shots.

 

[6ShotsOr5?]

oops, ledd beat me..... faster typer

Faster, but shorter probably had something to do with it too! So cool, here we are talking sine waves, and earlier I was reading somebody’s post with F=ma! If I knew you guys liked to talk dirty like this I would have been on here years ago.

 

[6ShotsOr5?]

My perspective as a newcomer is that we are trying to optimize a system that has some variability according to shooter performance and shooter technical expertise, and the system factors are also changing as we conduct the tests. Looking at Donovan’s 1000 yd 6Dasher ladder test, I think “well 33.2 looks good, but let me shoot a few more, and hope the conditions haven’t changed since I drove down and back to check the target” - because I don’t have one of those WiFi setups, and I hope my focus was perfect, because I know I can never get my cheek back on that rest in exactly the same spot! In addition to the charge weight and jump/jam, we’ve got barrel temperature, atmospherics, etc. When we shoot another 100 rounds and have a little more erosion, we can seat the bullet longer, but we have added a little more volume to the area behind the bullet when it hits the lands so the pressure curve will still be different for the same powder charge. On top of all this is the usually small but significant variation in powder load / burn rate that we just call MV spread, and a little shooter error. And what we are trying to do is minimize the variation in system performance so that it’s less than the variation in shooter performance, which is definitely more variable for me than for most of you. The last part is why some of you are concerned about 0.02 gr when I would not be able to tell the difference ... yet. If you’ve see any high-speed photography of a barrel whipping around, and you think about all these other variables, and then you’re going to throw in some wind and, oh let’s put 5 or 12 flags between here and the target, what some of you people are able to do in terms of repeatability is truly mind boggling. My hats off to you! I think I’m gonna stick with ringing steel for awhile...

 

[Curious]

I appreciate that my own testing could jive me the answers Im looking for but like everything in life I have to balance my testing with time, cost etc so Ive never managed to do this yet, thats why I ask the collective from time to time if they have done what I propose?

Something that sill leaves me wondering right now is this;

I usually start by tuning my powder charge at a nominal seating depth, generally this would be 20 thou off unless I have historical data that showed me a particular bullet liked a certain jump/jam, all testing is then done and the powder charge is established. I usually use and OCW style test at 100, 200 or 300 yards to establish powder charges, depending on conditions. On small cases this will be 0.2gr increments or 0.1gr to fine tune.

Next I go on to seating depth tuning, I tend to load a batch of ammo long, say 50 thou past jam length and I then seat the bullets at the range at various lengths as I need them. If my OCW testing has shown the seating depth might be close, say groups in the 0.5" or smaller I will often start by moving 5 thou forwards or backwards to see what effect, sometimes adjustments will be more or less corse than 5 thou depending on groups sizes, I rarely see 2 thou making any difference. Often I will only fire two shots because if the trend is showing the groups are opening I will go the other way. Generally 30-40 shots is enough to get the groups tightened up and there will be enough ammo left for one or two 5 shot groups to verify.

I do wonder though if the original powder charge that looked so sweet at say 20 thou off has been affected if my final seating depth tuning that say now has me at 5 thou jam or any other length different to 20 thou off?

I guess what Im trying to find out is if the seating depth adjustments are affecting the harmonic vibration tune or if they are just timing the bullet exit into sync with the harmonics? Or in other words does one affect the other or are they working independently to achieve an optimum?

I suppose I could always go back to a fine adjustment powder charge test once the optimum seating depth has been found and that would tell me?

 

[Alex Wheeler]

I appreciate that my own testing could jive me the answers Im looking for but like everything in life I have to balance my testing with time, cost etc so Ive never managed to do this yet, thats why I ask the collective from time to time if they have done what I propose?

Something that sill leaves me wondering right now is this;

I usually start by tuning my powder charge at a nominal seating depth, generally this would be 20 thou off unless I have historical data that showed me a particular bullet liked a certain jump/jam, all testing is then done and the powder charge is established. I usually use and OCW style test at 100, 200 or 300 yards to establish powder charges, depending on conditions. On small cases this will be 0.2gr increments or 0.1gr to fine tune.

Next I go on to seating depth tuning, I tend to load a batch of ammo long, say 50 thou past jam length and I then seat the bullets at the range at various lengths as I need them. If my OCW testing has shown the seating depth might be close, say groups in the 0.5" or smaller I will often start by moving 5 thou forwards or backwards to see what effect, sometimes adjustments will be more or less corse than 5 thou depending on groups sizes, I rarely see 2 thou making any difference. Often I will only fire two shots because if the trend is showing the groups are opening I will go the other way. Generally 30-40 shots is enough to get the groups tightened up and there will be enough ammo left for one or two 5 shot groups to verify.

I do wonder though if the original powder charge that looked so sweet at say 20 thou off has been affected if my final seating depth tuning that say now has me at 5 thou jam or any other length different to 20 thou off?

I guess what Im trying to find out is if the seating depth adjustments are affecting the harmonic vibration tune or if they are just timing the bullet exit into sync with the harmonics? Or in other words does one affect the other or are they working independently to achieve an optimum?

I suppose I could always go back to a fine adjustment powder charge test once the optimum seating depth has been found and that would tell me?

Yes it has.

 

[Curious]

Yes it has.

Thats interesting Alex, can I ask what you have seen that confirms this and how do we combat the problem?

 

[Alex Wheeler]

I was in my ballistics laboratory analyzing the hard data from the super computer when I ... just kidding. I just shoot and see that the powder charge can move when you change other parts of the load. Just revisit the powder charge testing when you make other changes to the load. Everything is tied together to a point.