Teach me about "Ladder Testing"

[orygun]

I'm a self taught reloader. When I bought my first reloading equipment 30+ years ago the friend I bought it from gave me a quick rundown on how to work the process and handed me an old Lyman manual. I bought a new Hornady manual and cautiously started loading 41 Mag. After I didn't blow my gun or myself up, I progressed to other calibers and then bottle neck cartridges. I've learned several things the hard way, like squib loads (don't run 38 Special charges in a 357 Max case, even with soft lead bullets), over lubing cases, under lubing cases, etc. I've even "progressed" to fireforming for Improved cases and the old school method of sooting bullets to find the leade.
What I'm having a hard time wrapping my head around is ladder testing. Poking around the internet gives a few different ways to do it, but it seems like opinions on how to perform this testing, or it's actual value are widely different.
I get the jist of it, have a chronograph and a good place to shoot 100 yards, but not 300 like mentioned by some.

So, what can you guys teach me?

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[arrowshooter]

My understanding of ladder testing is that you are able to find a load that works best with the "harmonics" of your barrel. Harmonics of a barrel would be good to google. After gathering as much "data" as I can find on my particular combination, I will run a ladder from midrange to near the top. I also start out at the COAL recommended by the bullet manufacturer which has served me well. The ladder will be in .5gr increments, 3 shots each, over a chrono at 100 yards (which you know). Shooting with a solid bench rest is also important which you can see in the photo below.

Here is a recent ladder I did with my first 180gr Elk load. I was kind of in a rush because it was sprinkling and totally muffed the two targets on the left because I did not reset my rear bag on the shift over, opting to just "lean" over for the shots. So it's not perfect, but you can see which load I chose.



I stopped here, but there is more to the equation if you wish to shoot way the bubblegum out there. This includes breaking down a certain point in your .5gr ladder to say .2 grains, along with playing around with the COAL to get the perfect "jump" to the lands for your bullet.

This is just the gist of all that you have discovered so far. Good luck and have fun with it.

 

[DizzyJ]

I do a similar method, but don't shoot over a chrono until after I get my load (accuracy wise). Smaller calibers like the .223 I vary the charge by 0.3gr

Larger calibers like .308 I vary the initial charge by 0.5gr

Then fine tune with a smaller charge weight and bullet seating depth if you so choose.

 

[daved20319]

^^^This^^^. Although since I have a Labradar, setup is so easy that it goes with me most of the time, and I tend to chronograph almost everything when I do use it. I'm finding that my Creedmoor prefers longer seating depths, so I'm now starting at ~.010" off the lands for initial testing, then may go a bit longer or shorter and see if it makes a difference. Still lots to learn, and lots of other things to do, maybe, in my quest for 1K yard adventures. Bottom line, pick a system or technique that works for you and stick with it. Later.

Dave

 

[Member 34319]

I always thought it was to do with finding the charge that produced the most consistent bullet velocities.

This is my usual "ladder loading"

Say 223 for example.

Loading a 55 grain bullet.

You would load and shoot these powder charges.

Say

22.0
22.5
23.0
23.5
24.0

Say you found that 23 and 23.5 resulted in the lowest spreads and best results on paper. Then you load and shoot.

23.1
23.2
23.3
23.4
23.5

Etc.

I usually load 10 of each shooting both at paper and through a chronograph.

 

[flashpan]

I'm a self taught reloader. When I bought my first reloading equipment 30+ years ago the friend I bought it from gave me a quick rundown on how to work the process and handed me an old Lyman manual. I bought a new Hornady manual and cautiously started loading 41 Mag. After I didn't blow my gun or myself up, I progressed to other calibers and then bottle neck cartridges. I've learned several things the hard way, like squib loads (don't run 38 Special charges in a 357 Max case, even with soft lead bullets), over lubing cases, under lubing cases, etc. I've even "progressed" to fireforming for Improved cases and the old school method of sooting bullets to find the leade.
What I'm having a hard time wrapping my head around is ladder testing. Poking around the internet gives a few different ways to do it, but it seems like opinions on how to perform this testing, or it's actual value are widely different.
I get the jist of it, have a chronograph and a good place to shoot 100 yards, but not 300 like mentioned by some.

So, what can you guys teach me?

Here is one good site to learn about precision hand loading ... focused on rifles.

Load Development Analysis

Determination of the optimal load for your rifle necessarily includes some form of analysis. In this episode we cover load development analysis – as a follow-up to the very popular 6.5 Guys L…

www.65guys.com

 

[orygun]

Thanks for the info, guys.
One version I read involved shooting one round each of the laddered charges at a target, over a chrono watching the vertical stringing and fps gain, then working within the range of charges where the velocity flattens out and the stringing seems more of a cluster.
Does this make any sense?

Also, I assume that there are really two ladder tests to run. One for velocity, then one for bullet seating depth. Correct?

 

[Krabbe]

Thanks for the info, guys.
One version I read involved shooting one round each of the laddered charges at a target, over a chrono watching the vertical stringing and fps gain, then working within the range of charges where the velocity flattens out and the stringing seems more of a cluster.
Does this make any sense?

Also, I assume that there are really two ladder tests to run. One for velocity, then one for bullet seating depth. Correct?

I run a ladder test to establish a starting point for powder loads. I run three shot groups to establish seating depth.

 

[orygun]

I run a ladder test to establish a starting point for powder loads. I run three shot groups to establish seating depth.

Care to define your version of the ladder test?

 

[DizzyJ]

One version I read involved shooting one round each of the laddered charges at a target, over a chrono watching the vertical stringing and fps gain, then working within the range of charges where the velocity flattens out and the stringing seems more of a cluster.
Does this make any sense?

Also, I assume that there are really two ladder tests to run. One for velocity, then one for bullet seating depth. Correct?

That's one method. However, those that use it need to be extremely meticulous on every step of their loads in order to see actual true flat spots in velocity.

The 2nd one I wouldn't personally call a "ladder test". I just call it a bullet seating test for the final "fine tune" looking to shrink the groups.

I generally start at or close to the lands and back off by .005" each load up to about .030" off in order to find the sweet spot.

If you do this however, make sure to work up the powder charge portion with the bullet touching or slightly jammed into the rifling as this is where the pressure will be highest.

You don't want to work up a hot accurate load and then start jamming into the lands afterward, as pressures will spike immensely.

 

[saxon]

for instance 110 varmagedden in 300 blackout
starting is 14 grain 2400 @2047 fps max is 16 grain @2228 fps
string of 5 shots ea for best group with two grain increases
from 14 to 16 best group is at 15 grains @2137 fps
the stated COAL is 2.025 another string of 5 shots ea seating from 2.020
to 2.030 and 2.025 is best as they stated in my rifle one ragged hole @ 75 yards for required expansion FPS to work as advertised
BC = .310
SD= .166
mV = 2,100fps
Term Threshold = 1,800fps
MAX = 125yds

 

[P7M13]

Reading on "ladder tests" over the years confused the heck out of me. Lots of varying ideas on how to do, etc. Haven't looked at @flashpan's site suggestion yet, but surely will. The idea is to search for the load that will produce the lowest ES and SD on a chronograph.
Some will say, use a chrony, focus on the same spot, look for the minimum vertical dispersion cluster and verify with the chrony reported speeds.
For example, I will load up 20 rounds in .3 grain increments for a cartridge, shoot them over my chrony and look for the flat velocity spots. They are usually marked at the high end by a jump in velocity. Then look at the target. I'll then load 5 of each of the flat velocity rounds that had the least vertical dispersion.
Then I'll do a group testing of those loads and select the ideal.
@arrowshooter's example above, I would call it more of an optimal charge weight test, or OCW. Those are the easiest to understand, because it takes into account the harmonics of the barrel and how the whole system interacts with you.
If you're using a barrel mounted chrony like the Magnetospeed, it acts like a barrel dampener, so affects the harmonics of your shot and POI.

 

[Krabbe]

Care to define your version of the ladder test?

I load ,starting from minimum to maximum, in.5 grain increments. I then fire these loads over a chronograph and record each velocity/powder charge. I set up graph paper when I start and record as I go. Somewhere on the graph you will hopefully get a flat spot between two loads. I then use this as a starting point to tinker with the OAL/ distance from lands etc. It is possible to have more than one plateau.

 

[Spitpatch]

I found it curious (even with the thread topic recognized) that no post here talked of what needs to happen PRIOR to any "ladder testing".

Probably the most important first step in working up a load for a "new" (to the shooter) gun is bullet selection. It is imperative to narrow bullet selection (to one bullet) before incremental powder charges can be examined. NEVER examine more than one change at a time (ie: powder charge and seating depth or bullet). BULLET CHOICE IS PROBABLY THE SINGLE MOST INFLUENTIAL COMPONENT TO AFFECT ACCURACY (which is why we examine that variable first).

Examining different bullets while at the same time examining charge weights, seating depth, primers, etc. is statistically problematic at face value, let alone impossible to control the multiple variables.

Bullet selection might be very simple: a recent thread here examined load workup in a .25-06, with the shooter fully dedicated to a Nosler Partition bullet with the purpose being elk hunting. For this shooter, over half his work is done. Goals of velocity and accuracy (with a safety issue addressed) are all that now trouble him.

Define the purpose of your load. This will narrow your bullet choices. Gather your bullet candidates for that purpose. Consult the books (PLURAL!) and cross-reference them for choice of powders. Look toward loads/powders that approximate full volume filling of the case while still achieving high velocity. Glance at "recommended loads" (Sierra's "accuracy load" and "hunting load" are examples, as well as asterisks in some manuals designating "most accurate powder", etc.). This may supply you with a good "test engine" (subject to change later) for testing your bullet candidates.

For each of your bullet candidates, a safe, "generic" seating depth will be chosen (not really pulled out of thin air, but we want a constant here not to be fiddled with with respect to that bullet). We may assume at this point that all bullet candidates are in the same weight RANGE (relating to purpose). With your load book research, ONE powder has been selected as your test engine.

It should never be necessary to begin load research at the bottom of charge weight range (unless a low-velocity/recoil load is the purpose).

With a book load slightly less than maximum ("slightly less" will mean something different for different cartridges), feed your bullet candidates a charge that is at least comparable if not identical, and record chrono readings and note accuracy. In nearly EVERY instance, one bullet (maybe two) will shine above the others in your gun. If it is a bullet that also fulfills your stated purpose for the load (for expansion, etc.) you have arrived. If there is a close contender, do not toss it by the wayside. It may be the one that shines when other variables are changed. For bullet selection, I rely on three-shot groups in the interest of component frugality.

With your bullet selection complete (and verified with repeatable results), you are now ready to change other things ONE AT A TIME. Powder charge might be your next component to examine. Watch the chrono as you increase your charge in amounts appropriate to the cartridge. (Half a grain in a .221 Fireball is consequential, while in a Weatherby hardly noticed). As charges increase, SD (Standard Deviation) should diminish, then flatten, then get "squirrelly". Squirrelly is bad. Go back some and find out what charge is below the tipping point.

You now have a "candidate" of powder and charge. You may try another powder (attractive in your book research) with reference to (and benefiting from) the baseline you established with powder #1. You know at what pressure (velocity is the readable indicator) things get squirrelly. Don't go there again.

With a bullet chosen, a powder and charge chosen, you can then fiddle with your seating depth to refine your generic approximation that you have NOT CHANGED until now.

Primers might be examined after all the above but rarely do I depart from my original vehicle (chosen for cartridge, quality, and book recommendations for the cartridge/powder type and charge amount). A Magnum primer sometimes changes the game measurably (reduce your load for it a bit).

The important thing is to ONLY CHANGE ONE THING AT A TIME to test. Also: DO NOT live and die on Standard Deviation. Low SD's VERY OFTEN DO NOT TRANSLATE TO ACCURACY. Even your target choice should not change.

I would never own a Chronograph where I began to rely on a "printed" readout for my data. Pen and Steno Book allows the shooter to record by hand the results, and in so doing the opportunity is literally IN HAND to make incidental notes that later may be invaluable. Strips of inkjet paper disregard the importance of personal observation and documentation.

If you cannot look at your load information 20 years from now and clearly draw conclusions from the information you produced and organized today, all your efforts are USELESS.

 

[orygun]

I'll get to work loading up some test ammo this weekend. Might even get a chance to shoot some of it.

Thanks to all for the replies.