Help me analyze my ladder test

[cconn]

I just started into longer range shooting. Shot this ladder test today @ 375 yard, farthest I can shoot in my backyard currently. This is also the farthest I have ever shot.

Loads are .308 Winchester, Lapua cases, 175 grain SMK 10 thou jammed. Varget powder.
#1-#3 ended up off paper in the dirt.
#4- 41 grains
#5-41,5
#6- 42
#7-42.5
#8-43
#9-43.5
#10-44
#11-44.5
#12-45
#13-45.5
#14-46 (14, 15, and 16 shot 30 minutes after previous shots)
#15-46.5
#16-47 (primer slightly cratered, stopped here)

I am thinking concentrate on 11, 12, and 13 for further refinement. What say the hide?

 

[MALLARD]

Re: Help me analyze my ladder test

i agree with you ,but i might do 11-15 just to see what happens. How did you keep track of what hole came from charge weight ? Did the wind pick up on shots 14-16 ?

 

[cconn]

Re: Help me analyze my ladder test

I painted the bullets with different colored markers. After shot 13 I had to go pick up my son from school and was gone 30 minutes. Wind was a little more when I got back.

 

[bigwheeler]

Re: Help me analyze my ladder test

14 and 15 look best to me. It looks like you just went over a node with 15. So
14 would be my choice. With half grain powder jumps you should have some
lee way in the load being forgiving. 12 Would be my second choice, just do to
velocities.

 

[pjparker]

Re: Help me analyze my ladder test

In a ladder test you are looking for the point where you have the minimum amount of vertical dispersion.

This indicates the point in the barrel's oscillation cycle where it is approaching a peak, reaching that peak, and then returning in the opposite direction.

Ideally, the velocity that centers on that peak will give you the least vertical dispersion. It appears to me that you have a node in the vicinity of the 3 shots just to the left of your orange bull.

Shots 11, 12 and 13 appear to me to be a poor choice to further investigate. I would interpret those shots to be travel from one node to the next, meaning that a small change in velocity would assure you a larger vertical dispersion.

Paul

 

[mjh30]

Re: Help me analyze my ladder test

cconn, you stated you are new to long range shooting, bring it in a bit and start over. As pj stated above you are looking for the least amount of vertical spread. I think you have to load and shoot at least three, and preferably five rounds of each load to see how well they group. The groups will open and close back depending on how close to a tuning node the charge is located. You are shooting at 375 right, just look at your target 14 is above 15, is that 4 and 9 above 8, do yourself a favour bring it in to about 200 and start over, then work your way out there. By the way, what are you shooting is it a factory or custom rifle. Heres a link to a ladder test conducted by another Hide member, take a look at it, its very informative.

 

[Headgear]

Re: Help me analyze my ladder test

I'm not so sure that bringing it in to 200 is going to help. I have better luck at 300 to 500 because there is more separation between the impacts of different charges. But maybe that's just me.

I do agree however that running 3 to 5 tests will give a better overall indication of the results. I have also read that each test should be rotated starting with the lowest charge round and go up and then the next test should start with the highest charge and go down. Here's a link:

http://www.6mmbr.com/laddertest.html

It looks to me that you have two accuracy nodes. I can't read the numbers for the group just left of the bullseye but it and then again 13 and 14 look pretty tight. If you draw a horizontal line between them and then measure the vertical separation of the lines, those two look to be the closest. I would run the test again from 44 up (less than 44 is going to be too slow at longer distances with a 175) and do it 3 to 5 times. Where ever the highest sweet spot is, run another test from what appears to be the center of the tightest vertical spacing. Then load rounds in .2 grain increments starting a grain below that center and go up to a grain above the center to find the true center. That should show you where you need to be.

Try to get your rig as rock solid as you can. I don't mean to over state the obvious but the test results are only as good as the shooter, rifle, ammo and conditions. Thats why repeating the test is a good idea before relying on what you see on the paper.

I hope you find the node, refine it and end up shooting some tiny little bug holes.

Good Luck!

 

[armymedic.2]

Re: Help me analyze my ladder test

+1 mjh. over 300 is a long way to shoot for info if you are still mastering basic form.

 

[vman]

Re: Help me analyze my ladder test

mmmmmmmmmm....

ok sounds like a pain in the ass, BUT if you could start from about 43 and work your way back up to 46.5 but this time, send two flyers down to hit paper, and then shoot the rest in a string, no need to smash it out fast, but do it within a 10 minute window.

make sure your form is solid and consistent. Do it prone if you can and watch your breathing, trigger squeeze, and all of the other basics.

Im guessing 13, 14 and 15 should have been a little closer together, but its hard to tell considering the breaks in time and potential shooter error (if any).

Also, you could load about 5 rounds each, say 45.0, 45.3, 45.6, 45.9, 46.2, 46.5 and do an OCW test in round robin form.

That, combined with a ladder will give you solid info. If you have access to a chrony even better, as consistent MV is indicative of a node.

Happy shooting.

Vin

 

[pjparker]

Re: Help me analyze my ladder test

vman makes some good points.

Narrow the charge increment to .3 grs instead of .5grs - gives you better resolution.

I would shoot the ladder test again one shot at each .3gr increment to zero in better on where the nodes fall. Do this in one session to avoid condition changes, but only the vertical dispersion is what we're looking for.

Pick a cluster and shoot some groups that bracket that cluster. 3 shot groups should be good enough here, though.

Go to 5 shot groups to verify results of the 3 shot groups, or just pick the tightest 3 shot group, losd a bunch and GO SHOOT ......


Paul

 

[Gregg Jacob]

Re: Help me analyze my ladder test

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cconn</div><div class="ubbcode-body">I just started into longer range shooting. Shot this ladder test today @ 375 yard, farthest I can shoot in my backyard currently. This is also the farthest I have ever shot.

Loads are .308 Winchester, Lapua cases, 175 grain SMK 10 thou jammed. Varget powder.
#1-#3 ended up off paper in the dirt.
#4- 41 grains
#5-41,5
#6- 42
#7-42.5
#8-43
#9-43.5
#10-44
#11-44.5
#12-45
#13-45.5
#14-46 (14, 15, and 16 shot 30 minutes after previous shots)
#15-46.5
#16-47 (primer slightly cratered, stopped here)

I am thinking concentrate on 11, 12, and 13 for further refinement. What say the hide?
</div></div>

Is there a target pic with this that I'm not seeing

 

[vman]

Re: Help me analyze my ladder test

Yes and it appears in your quote also

 

[CMH]

Re: Help me analyze my ladder test

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mjh</div><div class="ubbcode-body">cconn, you stated you are new to long range shooting, bring it in a bit and start over. As pj stated above you are looking for the least amount of vertical spread. I think you have to load and shoot at least three, and preferably five rounds of each load to see how well they group. The groups will open and close back depending on how close to a tuning node the charge is located. You are shooting at 375 right, just look at your target 14 is above 15, is that 4 and 9 above 8, do yourself a favour bring it in to about 200 and start over, then work your way out there. By the way, what are you shooting is it a factory or custom rifle. Heres a link to a ladder test conducted by another Hide member, take a look at it, its very informative.

</div></div>

I am not seeing a link here ????