6BR improved VLD tuning. Powder charge then seating depth?

[Boatschool02]

All,
Fully acknowledge the sequencing theory has been discussed ad nauseum.
Just an interesting occurrence and a follow on question.

Brux 8T 29" straight taper, 0.100 Freebore, 0.272 neck, light turn 0.268 loaded round.
Berger 105 VLD-T trimmed and pointed
H4895 & CCI 450

Settled on 30.8 grains of H4895 after 2x double 4-shot group ladder tests from 30.4-31.0 in 1/10th increments at 300 yards.
Running +/- 2925 FPS

Second attempt on seating depth test.
Tough wind (15+ mph) last time. Moderate (8-10mph) wind today, but awful mirage. (The test may be mostly invalid anyway given the doubling of typical vertical and windage.)

From left >>> right: 0.010 in, 0.005 in, 0.005 off, 0.010 off touch @ 200 yards.
Top and bottom rows are identical, repeat tests after cleaning and cooling.
-- The wind did NOT appreciably let up during either of the two groups on the far right.

Both trips to the range, the longer "jumping" depth has knotted right up producing sub 0.2 MOA groups at both 200 and 300 yards. Several groups at 300 yards have had 3 of 4 shots under 0.400."

Question: Which, if any, of these conclusions would you be inclined to accept?
1. Too much wind or mirage. Test invalid, or
2. This barrel and this lot of VLDs actually prefer JUMP over jam, or
3. Because I conducted my charge weight testing, first, at 0.010" off, all I'm really seeing is the seating depth test reaffirm the seating depth that was used during the charge/velocity tuning?
(If wanting to test this theory, would you rerun the charge testing at say 0.010" *in* and see if it yielded a different velocity node?)

Any/all feedback welcome.
Thanks,
Luke

 

[retired]

if your initial test was 4 shot groups, it was not a ladder. just group shooting. nothing wrong with group shooting, but you seem to have shot a bunch and do not have an answer. they all seem to have some vertical. i think you are still searching many bullets later.
may i suggest a real ladder.

 

[mikeeg02]

Personally I'd shoot the top right one again for confirmation (make sure it is repeatable) and try it again with same seating depth and another with .1 more powder. I would also try it + and - .002 on seating depth with original charge. .005 in steps in seating can be big jumps, but can find flat spots.

Adding .1 to the top right group may take a little bit of the vertical out.

But I don't always go about things the right way.

 

[mikeeg02]

Also, have you checked ever loaded round base to ogive? How consistent were they to begin with?

 

[Boatschool02]

This is one of two charge weight tests at 300 yards.
Apologies if I "misclassified" this as a ladder. (Aim points plotted exactly parallel, target level = same effect?)
In group and between group vertical dispersion decrease appreciably in the 30.7-30.8 range.
(Top 30.8 measures 0.470" and lower was 0.330" vertical at 300 yards @ default/initial seating depth.)
Vertical today at 200 (bad mirage) was twice normal but consistent.
-
Interested in similar or contradictory experiences with VLD seating & experience potentially "decoupling" the sequencing of charge weight to seating depth testing.
Thanks,

 

[Boatschool02]

Thanks for the input.
-
My previous test was in 0.003" increments working back from touch, but I had neck tension/seating force issues so my lengths were atypically aberrant.
Today, I wanted to see if the groups could be bettered by going in past touch.
For this batch, my COALs were all under 0.001. I added a mandrel step and use a custom inline seater.
I have not started sorting by bearing surface or seating effort, yet.
I'm by no means tied to jamming the VLDs. I've just seen some very small groups (this lot, this barrel) in and around this range and figured it was worth seeing if others have had a similar experience.
-
Appreciate the input on upping the charge weight. I'm new to interpreting these groups and my Labradar just stopped working this afternoon.

 

[mikeeg02]

I've personally never done ladder tests. But from what I understand they should be done at your intended distance.

I group shoot at 200 and adjust until it's consistently sub .5" round groups which typically nets me a ~6" gun at 1k paper which is not my forte. That's obviously not Tom M good, but I shoot very well at 850-1k steel silhouette at ridgway. Better 1k paper shooters than me tune until it's consistently sub .5" at 300.

I only sort bullets by weight. If I wanted to be more competitive at 1k paper I'd sort them farther, but I always weigh primers and cases too. That's as far as I'll go. Not advocating to follow my lead, just letting you know where I'm comfortable with.

Also to be clear, 5 shot, sub .5" round groups. When testing and searching I start with 3 shot groups to save on bullets and barrels.

 

[Gabe22BR]

I changed powders, left 4895...now starting over myself..

 

[T 700]

I'd try Varget and RL-15

 

[retired]

well long enough to see what is happening. 100 is too short, 200 marginal 300 is better.........

I've personally never done ladder tests. But from what I understand they should be done at your intended distance.

I group shoot at 200 and adjust until it's consistently sub .5" round groups which typically nets me a ~6" gun at 1k paper which is not my forte. That's obviously not Tom M good, but I shoot very well at 850-1k steel silhouette at ridgway. Better 1k paper shooters than me tune until it's consistently sub .5" at 300.

I only sort bullets by weight. If I wanted to be more competitive at 1k paper I'd sort them farther, but I always weigh primers and cases too. That's as far as I'll go. Not advocating to follow my lead, just letting you know where I'm comfortable with.

Also to be clear, 5 shot, sub .5" round groups. When testing and searching I start with 3 shot groups to save on bullets and barrels.

 

[JEFFPPC]

well long enough to see what is happening. 100 is too short, 200 marginal 300 is better.........

I will take issue with 100 is too short. If it will shoot in the .1's at 100 with good ES it works at 1000 in my experience if you have good bullets.

 

[retired]

the question was about shooting a LADDER, not shooting GROUPS.

I will take issue with 100 is too short. If it will shoot in the .1's at 100 with good ES it works at 1000 in my experience if you have good bullets.

 

[mikeeg02]

Did you do any testing over the weekend ? Any updates ?

This was what I did at 200 yards last weekend.

I shoot three first round to find what needs tested again.

The first is a group of three, showed a little verticle stringing.



Same load but with .1 more powder. All else the same. Pretty much cut the verticle in half. And made a nice round group.

5 shot group though.

 

[Boatschool02]

Sorry,
Not yet. Strange weather. Hoping to go this weekend.
Thanks for the follow-up.
-
Went back to my notes and targets for 185 juggernaut tuning as well.
Same occurrence. Generic seating depth used during charge selection ends up testing near the top on later seating depth testing.
Just wondering if others have experienced similar and if anyone is accounting for that, or potentially designing testing routine to avoid it. Maybe the effect is less pronounced out past 300 yards?
Thanks,
Luke

 

[urbanrifleman]

So, you went up .1 and it cut the group in half. That group looks amazing. I would then test .1 on either side of that to verify. .1 low and .1 high, and one centered. Shoot three and see if it repeats.

I am still have a problem that .1 grain puts the load in tune and .1 puts it out of tune. There are literally dozens of factors that could have changed that group besides that change in powder charge.

Unless you have one of those grain by grain throwers, I doubt it is possible to throw charges to within .1 with any real repeatability. Oh, how I would love to apply one of those Six Sigma capability tests to these magic powder throwers to show there capability. I am just going to guess they are simply not repeatable by any real world test of manufacturing tolerance. Anyone who comes from manufacturing/assembly knows what I am talking about. Even the most wiz bang tools out in the real world fall woefully short of repeatability when the tolerance is tighter than the true capability. It seems most of the tests I have seen on these powder throwers, they use one data point as the "control" or no control at all. They literally measure the scale and thrower against itself.

 

[mikeeg02]

It doesn't always work that way. The load was already pretty close. I was testing seating depths in .003 steps and I chose the one with the slight vertical string and added .1 grains. One seating depth .003 different had a nice group but not as round.

Yes I use a fx-120. Yes I calibrate it before every use. And yes I weigh charges to the kernel. (.02 grains) I can only assume others do the same.

And yes that group has repeated.

Mine is a 6br-a, with h4895 which seems to have narrow but consistent nodes.

 

[Rick300]

I have a newbie question regarding those narrow window loads - how do you account for big temperature changes? Let's say you developed that load on a cool March morning. What happens when it gets hot in July and you need to load up for a match?
I have run into this before and don't know what to do except look for a wider node.

 

[mikeeg02]

I generally use varget, and am trying h4895. Both are extreme powders that have albeit some, but very minimal temperature sensitivity. Those were shot at 45F, most of my shooting season is between 60-80F. I'll retest but I didn't have to change anything last year on my dasher.

I'm not saying what I do works for everyone. Just offering suggestions of what I'd try with the data given. If there was only one way to develop a load for competition, there wouldn't be a need for discussions about it lol

 

[retired]

you appear to be lost in the world of reloading.
the A&D fx120i does 0.02 grain with a .03 tolerance.
lots of people use them because they work.
as far as testing "thrown" charges, i have, with 2 others, we threw 100 charges each, of various powders and charted the results. been there done that. most suck, but not all.
finishing position in a match followed the skill or lack there of, of the person throwing powder.

I am still have a problem that .1 grain puts the load in tune and .1 puts it out of tune. There are literally dozens of factors that could have changed that group besides that change in powder charge.

Unless you have one of those grain by grain throwers, I doubt it is possible to throw charges to within .1 with any real repeatability. Oh, how I would love to apply one of those Six Sigma capability tests to these magic powder throwers to show there capability. I am just going to guess they are simply not repeatable by any real world test of manufacturing tolerance. Anyone who comes from manufacturing/assembly knows what I am talking about. Even the most wiz bang tools out in the real world fall woefully short of repeatability when the tolerance is tighter than the true capability. It seems most of the tests I have seen on these powder throwers, they use one data point as the "control" or no control at all. They literally measure the scale and thrower against itself.

 

[mikeeg02]

Did you get a chance to shoot last weekend? Or more bad conditions?