Ladder test load development data interpretation- advice/help/wisdom please

[SSL3O8H]

Hi Guys and Gals. I think I might be a good fit in this online community. I hope I can better myself here and eventually make myself a skilled reloader and shooter with your collective help and eventually become a respected contributing member.

I'm 1 year new to shooting and just preformed my first real precision set of handloads and accompanying ladder test yesterday. I'm a little bit confused by what the test results are trying to tell me. I'm hoping your collective experience can interpret some of this data so as to help me find what is probably is looking me in the face. So let me explain-

I will try to be as accurate as I can with my information. I've done this to the best means I know how although I'm sure I've made some mistakes or have holes in my data.

My lifes work background complements precision shooting as I have a fairly hefty background in code driven precision machining and metal fabrication, precision measuring, proof and witness testing, non destructive and destructive testing and accurate data collection, procedure development and process variable controls.

The rifle I used is, or I guess I should say "was", a new in box 1976 Sako L579, right hand bolt .243 win, 23" heavy varmint barrel 1:10 twist, and equipped with a Zeiss 4-12x power SFP 56mm scope held firmly with Sakos own optilock bases and rings torqued to spec and verified torque holding over 280 rounds during break in and seems to be holding zero tightly this far. The rifle thus far seems to prefer heavier bullets in the 80-95gr range, with a factory federal load printing a consistent sub 1 moa at 100yd with a fairly inexperienced shooter. Trigger has been stoned, polished and spring tuned and has no creep and breaks crisp and clean as glass on a -40 day at a nice 680 gram 1lb-8oz to 737 gram 1lb-10oz with little to no discernable over travel. I am a right handed shooter.

Brass is factory federal loads that have been once fired in the exact rifle.

Brass prep is as follows, deprime, citric acid ultrasonic bath spotlessly clean, primer pocket uniformed and chamfered, brass neck dimensions after being once fired was 0.280" O.D. After the neck was resized carefully with a Lee collet neck size die via a rotated multi step collet bite it measured out at consistent 0.2705" O.D after which I trimmed case length to 2.035" +/- 1 thousandths, and a light chamfer inside/outside deburr of the necks after trimming. Neck wall thickness before bullet seating was surprisingly measured fairly consistent at mostly 0.015" to rarely 0.016" thick, measured with a Starrett tubing micrometer. Bullet to case neck fit was about a 2.5 thousandths interference press fit.

Load data is as follows, Hornady 87 gr vmax bullets, loaded to COAL of 2.685" which is just kissing the lands verified by repeated oal measurements via Hornady OAL gauge. Assembled cartridges were finished with a rotated multi step crimp with a Lee crimp die. Crimp would be what I'd call a light medium crimp . Primers are federal premium, match grade large rifle primers fully seated, if not slightly overly seated. Powder is IMR 4350. The ladder test ammunition was loaded in twenty one rising .3gr increments, from 38 gr up to 44gr. Lee manual calls out a max load of 43gr in a 90gr bullets. Hornady doesn't call out a spec for IMR 4350 only H4350.

Powder charges were thrown light on Lyman gen 6 electronic powder dispenser scale and trickled up to charge weight on a RCBS m1000 beam scale tuned by Scott Parker and also has a magnification lens added for enhanced visual acuity. I've verified the scales accuracy using a set of f class mg weights prior to charging. Charge weight control was done with maximum care going as far as using tweezers for weight down to kernel precision.

Test shooting was conducted at 382 meters 418 yards in a mostly open field with a slight treed area to the left of the shooter for the first 50m. Shooting direction was strongly north due lesser east The physical target was a 4'x8' sheet of underlay plywood standing on end held in an A frame target holder with a spray painted orange circle centered for a consistent point of aim. Ambient temperature was 30c 86f with full sunshine during the hot humid mid clear afternoon day, wind data was taken from weather app on phone showing a 13 kph 8mph wind with peak gusts to 20kph 12.4 mph. I know I need to get a kestrel or even better a wireless field pole mounted electronic weather station. Wind was a 2:30 o'clock wind left to right, shooter being 6 o'clock and target being 12 o'clock. Barrel was cleaned and borescoped prior to test, no heavy copper fouling or heavy carbon fouling prior to test. Initially 5 foulers and 3 sighters were fired prior to the test starting. Barrel temperature was regularly taken at mid length with a temp of 43c 109f at start of firing of each 3 round group. A peak temperature of 49c 120f was measured.

Speed measurements were handled with labradar chronograph unit. The rifle was saddled nicely into a lead sled DFT 2 that was ratchet strapped down to my massive old hardwood cable reel shooting platform with an additional 18kg 40lbs of lead shot ballast on the sled.

An skilled observer was placed down range safely behind a heavy birm off to the left side of the shooter with a kowa 884 spotter and a two way radio and when safe, would run out and mark each shot one by one individually between shots directly on the ply wood throughout the test so as to know with absolutely certainty the data would be spot on correct. A side benefit was the time this took helped keep the barrel at a stable temperature range.

No pressure signs were encountered during the test with the test ending at 44gr. Each case was inspected with magnification and showed no primer flowing, crater nippling or prime flattening occured and no brass case head extractor witness marks or stiff bolt lift or extraction was noticed either. I'm sorry and wish I had prepared more cartridges with a higher charge weight which could of kept me going untill I got some discernable pressure signs.

I've made a spread sheet showing all twenty one 3 shot groups data. The data is comprised of charge weight, speed of each shot from that respective charge weight measured in FPS, and the ES of the charge weight and for what is not much worth, it's SD, then I show each groups size measured center to center and each groups verticle dispersion height measured center to center of the lowest to highest of the 3 shot group. I did not measure the horizontal dispersion as the wind was the likely largest culprit along with a small bit of me possibly. I will attach the spread sheet in a PDF version and in case it doesn't work for some I'll also attach a text version at the end of this all.

I will also attach a photo of the plywood before and after I've dimensionally laid it out. Each charge weight series is triangulated and under scored in red ink. The vertical dispersion is marked with horizontal lines along the side of the test that show the lowest and highest shot of that group. I suppose it gives a good indication to why it's called a ladder test eh?

I'm at a little bit of a loss and slightly disappointed. Although I'm very much new to this, I find the results vague and all over the map with nothing standing out at me. Other then a excellent tiny tight group in charge 11 @41gr charge weight, however it's fps don't make sense. For the most part FPS was all over the place and the verticle dispersion of shots didn't make sense when compared to FPS, and group sizes varied hugely. I took extreme care to prep the brass and even more care to careful and methodically weigh each charge and carefully fill the case as to lose no powder. The rifle was saddled nice and snug in the lead sled heavily weighted and strapped down to the bench. My point of aim my carefully placed to the best my ability dead center of the orange center marker on the plywood and rifle handled firmly with both hands. Now I do know the wind didn't help and I understand the horizontal dispersion is largely due to the wind and it's unpredictable gusts, but the verticle dispersion and fps seem to have no ryms to them and little usable data to me.

Thanks so much everyone, and happy to meet.


Quick Table

==============

Charge Weight : 38.0 gr
Shot 1 : 2273 fps
Shot 2 : 2788 fps
Shot 3 : 2768 fps
ES : 20
SD : 10.4
Group Size C To C : 1.800"
Group Vertical Dispersion : 3.840"
==============

Charge Weight : 38.3 gr
Shot 1 : 2825 fps
Shot 2 : 2829 fps
Shot 3 : 2818 fps
ES : 11
SD : 5.5
Group Size C To C : 4.550"
Group Vertical Dispersion : 0.750"
==============

Charge Weight : 38.6 gr
Shot 1 : 2822 fps
Shot 2 : 2829 fps
Shot 3 : 2818 fps
ES : 29
SD : 14.7
Group Size C To C : 3.900"
Group Vertical Dispersion : 1.750"
==============

Charge Weight : 38.9 gr
Shot 1 : 2845 fps
Shot 2 : 2880 fps
Shot 3 : 2881 fps
ES : 36
SD : 20.5
Group Size C To C : 4.470"
Group Vertical Dispersion : 1.370"
==============

Charge Weight : 39.2 gr
Shot 1 : 2904 fps
Shot 2 : 2907 fps
Shot 3 : 2891 fps
ES : 16
SD : 8.5
Group Size C To C : 4.850"
Group Vertical Dispersion : 0.915"
==============

Charge Weight : 39.5 gr
Shot 1 : 2891 fps
Shot 2 : 2927 fps
Shot 3 : 2897 fps
ES : 36
SD : 19.2
Group Size C To C : 6.800"
Group Vertical Dispersion : 3.040"
==============

Charge Weight : 39.8 gr
Shot 1 : 2941 fps
Shot 2 : 2952 fps
Shot 3 : 2931 fps
ES : 21
SD : 10.5
Group Size C To C : 1.970"
Group Vertical Dispersion : 1.780"
==============

Charge Weight : 40.1 gr
Shot 1 : 2991 fps
Shot 2 : 2966 fps
Shot 3 : 2980 fps
ES : 25
SD : 12.5
Group Size C To C : 4.150"
Group Vertical Dispersion : 2.750"
==============

Charge Weight : 40.4 gr
Shot 1 : 2992 fps
Shot 2 : 2975 fps
Shot 3 : 2966 fps
ES : 26
SD : 13.2
Group Size C To C : 6.800"
Group Vertical Dispersion : 4.340"
==============

Charge Weight : 40.7 gr
Shot 1 : 2977 fps
Shot 2 : 3002 fps
Shot 3 : 3013 fps
ES : 36
SD : 18.4
Group Size C To C : 1.680"
Group Vertical Dispersion : 1.350"
==============

Charge Weight : 41.0 gr
Shot 1 : 2999 fps
Shot 2 : 2981 fps
Shot 3 : 3031 fps
ES : 50
SD : 25.3
Group Size C To C : 0.500"
Group Vertical Dispersion : 0.320"
==============

Charge Weight : 41.3 gr
Shot 1 : 3031 fps
Shot 2 : 3019 fps
Shot 3 : 3015 fps
ES : 16
SD : 8.3
Group Size C To C : 3.660"
Group Vertical Dispersion : 3.625"
==============

Charge Weight : 41.6 gr
Shot 1 : 3056 fps
Shot 2 : 3050 fps
Shot 3 : Fault
ES : 5
SD : 3.5
Group Size C To C : 5.435"
Group Vertical Dispersion : 1.650"
==============

Charge Weight : 41.9 gr
Shot 1 : 3077 fps
Shot 2 : 3080 fps
Shot 3 : 3062 fps
ES : 18
SD : 9.6
Group Size C To C : 3.450"
Group Vertical Dispersion : 0.910"
==============

Charge Weight : 42.2 gr
Shot 1 : 3153 fps
Shot 2 : 3113 fps
Shot 3 : 3110 fps
ES : 43
SD : 24.0
Group Size C To C : 3.365
Group Vertical Dispersion : 1.360"
==============

Charge Weight : 42.5 gr
Shot 1 : 3129 fps
Shot 2 : 3150 fps
Shot 3 : 3120 fps
ES : 30
SD : 15.3
Group Size C To C : 7.250
Group Vertical Dispersion : 1.700"
==============

Charge Weight : 42.8 gr
Shot 1 : 3160 fps
Shot 2 : 3165 fps
Shot 3 : 3157 fps
ES : 8
SD : 4.0
Group Size C To C : 1.675"
Group Vertical Dispersion : 1.150"
==============

Charge Weight : 43.1 gr
Shot 1 : 3163 fps
Shot 2 : 3190 fps
Shot 3 : 3156 fps
ES : 34
SD : 17.9
Group Size C To C : 3.850"
Group Vertical Dispersion : 2.550"
==============

Charge Weight : 43.4 gr
Shot 1 : 3219 fps
Shot 2 : 3200 fps
Shot 3 : 3232 fps
ES : 32
SD : 16.0
Group Size C To C : 3.820"
Group Vertical Dispersion : 3.200"
==============

Charge Weight : 43.7 gr
Shot 1 : 3253 fps
Shot 2 : 3264 fps
Shot 3 : 3224 fps
ES : 40
SD : 20.6
Group Size C To C : 5.500"
Group Vertical Dispersion : 1.175"
==============

Charge Weight : 44.0 gr
Shot 1 : 3225 fps
Shot 2 : 3272 fps
Shot 3 : 3276 fps
ES : 51
SD : 28.3
Group Size C To C : 3.700"
Group Vertical Dispersion : 1.980"

 

[Dthomas3523]

Gonna move this to the loading forum.

I will say, you’re overthinking/doing this. Need to read this a few times to comment on it all. But lots of work done not needed to develop a load. Especially with a Labradar.

 

[spife7980]

I dont know about it being complicated... groups 10-14 seem to be indicating exactly what we are after with a ladder test.

 

[Dthomas3523]

I dont know about it being complicated... groups 10-14 seem to be indicating exactly what we are after with a ladder test.

View attachment 7368484
View attachment 7368485

Yea, but we only really look at positive compensation when there is a set range (like F class) we plan on shooting.

 

[spife7980]

While true in theory going off chrono numbers only with his data set is going to be a shit show.

12 and 13 would still win based on the numbers alone though.


Honestly, I would shoot 11 again and see if its repeatable no matter what your next step is. I dont care if the numbers are ugly if it shoots small, especially with an 87 vmax. And skip the lead sled. Put it in bags at least and actually shoot the rifle.

 

[Dthomas3523]

Any reason behind the crimping?

 

[Dthomas3523]

The chrono numbers are definitely all over the place. Something is off with the powder charge or the brass prep.

 

[spife7980]

The chrono numbers are definitely all over the place. Something is off with the powder charge or the brass prep.

Federal brass, crimped, spotless pure clean necks. Its about what I expect.

 

[SSL3O8H]

Hi guys,

Gonna move this to the loading forum.

I will say, you’re overthinking/doing this. Need to read this a few times to comment on it all. But lots of work done not needed to develop a load. Especially with a Labradar.

Thanks for the move and yes I think I am too. I have no one local to help me and I'm not very experienced to say the least. I should of reached out here before I started building up the loads.

Federal brass, crimped, spotless pure clean necks. Its about what I expect.

I used the federal brass as that's what I had, but I'm sure it's low quality in the big picture. As for the crimp, with my limited experience I chose to use a crimp it as I had the die and I've read that they can help uniform pressure build. However I will say I regret using it. I also think I over sat the primers with a bit to much force but I'm not sure if that would have a bearing on the numbers. As for the shotless clean necks, can one expand on that? Friction?

The chrono numbers are definitely all over the place. Something is off with the powder charge or the brass prep.

Power charge weighing was done as careful as I could do it. If I made a mistake at that stage it's beyond me what I did wrong. That's why I was disappointed with the fps story the chrono was telling me. I think the brass prep might be it.

Yes I agree the 10-14 range definitely is something that sticks out. It's the numbers that boggle me.

So should I be more looking at physical groupings regardless of the speeds?

I can make some more series 11s and put them down range to see if they tell a similar story, and I'll dump the sled and bag it.

 

[spife7980]

I used the federal brass as that's what I had, but I'm sure it's low quality in the big picture. As for the crimp, with my limited experience I chose to use a crimp it as I had the die and I've read that they can help uniform pressure build. However I will say I regret using it. I also think I over sat the primers with a bit to much force but I'm not sure if that would have a bearing on the numbers. As for the shotless clean necks, can one expand on that? Friction?

Its just not as nice or uniform as some cases with better reputations so expecting number results on par with the best is a faulty goal. Doesnt mean it wont shoot well.

With the factory brass necks being less than consistent compared to lapua or a turned neck the amount of crimp imparted on the bullet varies with the differences in neck thickness. I say let the sized brass do its job and not try to squeeze the two relatively solid items together into each other, the brass is already pinching enough.

And yeah, a bit of soot and carbon left in the neck acts as a lube and evens out the differences in friction from case to case.

 

[918v]

A suggestion:

When asking a question please be short and sweet. You wrote so much that you turned off most people reading this. Ask one or two questions at a time and you’ll get great answers.

 

[SSL3O8H]

A suggestion:

When asking a question please be short and sweet. You wrote so much that you turned off most people reading this. Ask one or two questions at a time and you’ll get great answers.

Noted- will do

 

[SSL3O8H]

Its just not as nice or uniform as some cases with better reputations so expecting number results on par with the best is a faulty goal. Doesnt mean it wont shoot well.

With the factory brass necks being less than consistent compared to lapua or a turned neck the amount of crimp imparted on the bullet varies with the differences in neck thickness. I say let the sized brass do its job and not try to squeeze the two relatively solid items together into each other, the brass is already pinching enough.

And yeah, a bit of soot and carbon left in the neck acts as a lube and evens out the differences in friction from case to case.

Yes, I understand what your saying. I was leaning on the fence about the crimp in the first place. I do believe it didn't help and regretted it.

As for case mouth carbon- how do you clean a case and still have the carbon deposits stay in the neck?

I do have a a pail of ultra fine moly powder for press fit assembly. All my cases are cleaned and preppo, so could I emulate a carbon deposit by moly application to the case neck interior to help to reduce friction?

 

[Jcrios014]

If you can run your data in excel and build a line graph with the data. Basically you're looking for the flat spots over the course of charges. If you would like I have a table built out and can email it to you if you like. just PM me.

 

[918v]

The main problem I see is you started with the bullet in the lands which gives you zero room to tune the COAL. Based on my 5 min of googling I would back the bullet off to .050” off and play in the 43gr area, then play with the coal.

 

[SSL3O8H]

The main problem I see is you started with the bullet in the lands which gives you zero room to tune the COAL. Based on my 5 min of googling I would back the bullet off to .050” off and play in the 43gr area, then play with the coal.

Ok noted, and good stuff. I didn't know where to start so I played it out like that. I've found so much conflicting info online about jump and jam and everything in-between i kinda was overwhelmed and said well just kiss the lands and start there.

Thanks for the pointer