Weird 100 yard Ladder Test Results?

[thefitter]

Little background first, I have 2 loads for this rifle (N550 & N540) that shoot pretty consistent .25moa at 100 and 200 yards. Last week I chronographed both loads and discovered that the ES was 45 and the SD was 14 for both. I was not very happy with the prospects for long range performance of these 2 loads so I decided to try a ladder test and see if I could start to work towards identifying a load that would hold vertical at long range.

I did 4 ladder tests with all the same components but 4 different powders. I started 2 grains over book max and worked backwards in .2 grain increments in my loading for 10 rounds of each powder. (Obviously I started shooting at the lowest load.)

I put a small ½” red dot at the bottom of the paper. As I shot each round I plotted impact on a separate sheet of notebook paper. I was expecting to see a vertical string as I went up in charge weight like I see in other posted ladder tests. As you can see it’s not even close to the other ladders I have seen.

While there are some areas that look like they hold vertical better, this is just not what I was expecting at all. I have no idea where to go from here.

I would have thought I would see some vertical with charges of 2 grains difference.

Also I should add that there were NO pressure signs at all. Weather was cold for here, 35-40 degrees Fahrenheit.

The only thing I really got from this is that N140 looks to be very promising at any weight.

Any ideas how to proceed would be greatly appreciated, thanks.

Or is 100 yards to close for a ladder test? I have 100 & 200 close by. It's a hour and a half drive to ge to a longer range.

 

[justinbaker]

Re: Weird 100 yard Ladder Test Results?

100 yards is way too close for a ladder test.

i would say 300 at least.

if you only have 1-200 yards to work with then go with OCW

 

[thefitter]

Re: Weird 100 yard Ladder Test Results?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: justinbaker</div><div class="ubbcode-body">100 yards is way too close for a ladder test.

i would say 300 at least.

if you only have 1-200 yards to work with then go with OCW </div></div>

I did that. But when I chronographed the loads they had a high ES & SD.

I'm going to try something at 200 yards next and see if I can see anything. Thanks

 

[EMorr]

Re: Weird 100 yard Ladder Test Results?

What is your goal distance you want to shoot at? ES and SD numbers are nice if you can get them small but if you are shooting at shorter distances, say less than 400 yards their effects are much less pronounced than at the longer distances. If the OCW test shows a load that grouped well at 100 yards I would try it at a longer distance to see if the results are repeatable ignoring the chrono data for the time being. Once you have a load that shoots and groups well at the distances you plan to shoot at you can make a batch to run over the chrono and tweak it if you don’t like the ES or SD numbers. Also your ES of 45 and SD of 14 while not as low as some strive for they are far from bad.

As others have said to run a ladder test you need a longer range and as you have seen firsthand vertical dispersion of bullets due to velocity differences at short range is almost none existent. Moving to 200 yards may help a little but I still don’t think you will be happy with the results, according to my ballistics calculator @ 200 yards my favorite load shows only .5” of vertical dispersion from a 100fps velocity change. Seeing as how your max charge weights are abound 45 grains you could move the rungs of the ladder a little further apart than .2 grains from each other, that will let you see things a little more clearly. Doing that once you find a good node you can bring the charges closer together in order to shrink the node if you want.

 

[thefitter]

Re: Weird 100 yard Ladder Test Results?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: EMorr</div><div class="ubbcode-body">What is your goal distance you want to shoot at? ES and SD numbers are nice if you can get them small but if you are shooting at shorter distances, say less than 400 yards their effects are much less pronounced than at the longer distances. If the OCW test shows a load that grouped well at 100 yards I would try it at a longer distance to see if the results are repeatable ignoring the chrono data for the time being. Once you have a load that shoots and groups well at the distances you plan to shoot at you can make a batch to run over the chrono and tweak it if you don’t like the ES or SD numbers. Also your ES of 45 and SD of 14 while not as low as some strive for they are far from bad.

As others have said to run a ladder test you need a longer range and as you have seen firsthand vertical dispersion of bullets due to velocity differences at short range is almost none existent. Moving to 200 yards may help a little but I still don’t think you will be happy with the results, according to my ballistics calculator @ 200 yards my favorite load shows only .5” of vertical dispersion from a 100fps velocity change. Seeing as how your max charge weights are abound 45 grains you could move the rungs of the ladder a little further apart than .2 grains from each other, that will let you see things a little more clearly. Doing that once you find a good node you can bring the charges closer together in order to shrink the node if you want.
</div></div>

Thank you. My goal is 1000 yards. That is the longest range I know of locally that I can drive to comfortably.

I will try .5 increments at the 200 next.

I'm also going to take a look at this N140. It's the first time I have used it in this combo and it looks promising.

 

[RemingtonSPS]

Re: Weird 100 yard Ladder Test Results?

Just by looking at your data i would take your N550 load and work farther with it. It looks like you have a node in the 46-47gr spread. I would load these and take them out to 300yds. I like to do latter testing at 300-500yds to minimize wind effects, i know your just supposed to look at vertical for a latter test but you can get tripped up by horizontal stringing from a bad load too like your N540 load stringing left to right and get fooled into blaming it on wind at longer ranges.

Here are my personal experiences which some would disagree with but it is what i have found in my testing....

Barrel harmonics or timing of the bullet, and shot to shot muzzle veloctiy consistency (ES and SD) are the two critical factors for a good long range load. To illustrate: I have seen high ES and SD loads group tightly at 500yds and closer because the extreme velocity didn't start to effect the load until longer ranges showing up as vertical spread. This was a good example of good <span style="text-decoration: underline">barrel timing</span> but bad muzzle velocity consistency. On the other hand i have seen good 1/2 to 3/4 minute loads hold that MOA at longer ranges due to good <span style="text-decoration: underline">ES and SD</span> but bad barrel timing.

What i found was if i did the latter testing it would show good ES and SD at longer ranges and once i had established the charge weight i would play with the seating depth of the bullet from .000" to jumping .120" and what i would see across the chronograph was the ES and SD tighten up a little bit more and the groups would shrink.

 

[RemingtonSPS]

Re: Weird 100 yard Ladder Test Results?

I would take your N550 load, shoot at 300 yards, and find your best ES and SD load. Then again at 300 yards test different seating depths (across your chronograph) and see which seating depth gives you the best ES/SD <span style="text-decoration: underline">and</span> group size.

At this point if your powder bullet combo isn't giving you the results your after change one. Only change one variable at a time i.e. powder, bullet, primer, etc. NOT all at once. If you have established a powder doesn't work, move on.

 

[thefitter]

Re: Weird 100 yard Ladder Test Results?

Thanks for the advise. But I'm not understanding why you say the N550. To me the N140 has less vertical. I think the horizontal string I got is the wind and poor trigger control. I was not trying to shoot groups and not focusing as much as I could have.

 

[RemingtonSPS]

Re: Weird 100 yard Ladder Test Results?

Thats what i mean about blaming horizontal stringing on wind when it can be a bad harmonic. When i do latter testing i always do it across a chronograph as well.

When the bullet impacts horizontally more than 2 1/2 times the tightest vertical it is usually an indication of horizontal stringing. But if you are not sure test it again across a chronograph.

The N550 load looked like there were several charge weights within an almost full grain spread that had less than .3" of vertical (46.4gr-47gr). That seems like a good starting point. Also they were all grouping roughly together on the horizontal plane.

It takes ALOT of wind to make that much horizontal spread at 100yds. If those loads where shot at the same day/time then why wasn't the 550 load effected by wind? Know what i mean?

 

[Criver600]

Re: Weird 100 yard Ladder Test Results?

Are you loading for a 308? I typically do ladder tests minimum 300 yards preferably at 600. .2 grain increments are just going to give a lot of confusing data. 1% of max case capacity is a good number .5 grain for a 308.

 

[thefitter]

Re: Weird 100 yard Ladder Test Results?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MuleHunter</div><div class="ubbcode-body">Thats what i mean about blaming horizontal stringing on wind when it can be a bad harmonic. When i do latter testing i always do it across a chronograph as well.

When the bullet impacts horizontally more than 2 1/2 times the tightest vertical it is usually an indication of horizontal stringing. But if you are not sure test it again across a chronograph.

The N550 load looked like there were several charge weights within an almost full grain spread that had less than .3" of vertical (46.4gr-47gr). That seems like a good starting point. Also they were all grouping roughly together on the horizontal plane.

It takes ALOT of wind to make that much horizontal spread at 100yds. If those loads where shot at the same day/time then why wasn't the 550 load effected by wind? Know what i mean? </div></div>

I see what you are saying now. I always thought horizontal was wind or the driver. You are saying it can be harmonics? I never heard about that, hence OCD ROOKIE.

The N550 at 45.2 is one of my great loads at 100yards. You think you see my higher node at (46.4gr-47gr)or above? I will play around that area. Thanks!

 

[RemingtonSPS]

Re: Weird 100 yard Ladder Test Results?

It's also good to fire your loads in a round robin method to keep as much of the mental part out of the testing. Was it wind, trigger control, being in a hurry? If you fire a string from all the same powder it can play with your head and you can start blaming a bad load on things that aren't really a factor i.e. wind etc.

 

[RemingtonSPS]

Re: Weird 100 yard Ladder Test Results?

I would load the full spread of 46-47gr at 300 yards and use a chronograph if you have one.

When i didn't have access to a chronograph i would do my testing at 500yds and out.

 

[RemingtonSPS]

Re: Weird 100 yard Ladder Test Results?

I'll give you and example of horizontal stringing.

The typical .308 load with 175's in a full value 10mph wind moves the bullet .75". What are the chances your wind that day was gusting from zero to 10 mph at full value? That is what you would need to see the horizontal stringing of your N140 load. That, and given your 550 load didn't have anywhere near that horizontal, tells me it wasnt wind.