ladder test

[porthos]

please explain how i would go about a ladder test for load development.

[kbstenberg]

If you go to You Tube type in ladder test for loading ammunition. You mite get 1 or 2 videos. I use them a lot.
My spelling prob. isn't correct. Look up Satterly load development. Kevin

[country gent]

I believe Criehton Audette came up with this ( He recommended it for long range rifle loads) It was part of a process designed to find the best load for your barrels harmonics.
The process was to load and shoot 1 round at .2 grn increments from starting to max for a given powder in a target, Accurately plotting each shot as its fired, either on a target besides you with spotting scope or in the pits if available. One of the new target cameras that plot shots as fired would be great here. What your looking for now is the points where 3 shots cluster together in a group. You make note of these points and the velocity of the mid point. Now load test groups at the mid point of these clusters nd shoot for actual groups. DO this which each powder you wish to test. Ypu end up with a load that can be +/- .3 and still fall in the same group. It helps you find the point where the bullet exits on a dead spot of the harmonics nodes.

Several things that help with this process
As stated one of the target cameras would be a big plus. A good spotting scope works as long as you can see bullet holes. SIghting in so your aiming at the bull and hitting above in the white may help also.

My wife and I did this as a team loading at the range she loaded each round while I shot chronoed and plotted them. I would take 2 targets and put gridlines on them 1" spacing to help with the plotting. I would mark shot number on the plotted target and velocity. The grid lines were a big help here.

When this portion of the test was done we took a break had a cold soda and looked over the results on both the plot target and fired target. Picking the test points We would load 10 shot groups at each point and test fire them for groups consistency and velocity. One of us would make a run for carry out too, but I always got to buy, lol. When done we normally had a very good load.

To ease loading at the range we brought a supply of primed cases.

200 yds is fair and 300yds is better. A lot of long range shooters use this tool to fid a load.

Im not sure I would go thru the trouble for most handguns other than the long range single shots

[sigep1764]

I load up 5 rounds from the bottom of the load data and 5 rounds every .2 grains. Then see which ones group well.

[Larry Gibson]

Audette developed his ladder method for use at one specific range (600, 800, 900 and 1000 yards I believe as he was a dedicated Palma and long range match shooter at the time). He was using an automatic charge trickler (one of the 1st made) to charge 300 Win Mag cases with 4350. The trickler threw charges with a +/- 1.5 gr difference. He came up with the "ladder" to test if there was a charge with a +/- 1.5 gr variation [example; a 68 gr "load" that the trickler would through 66.5 to 69.5 gr charges] that would possibly hit to the same point at the specific range due to barrel harmonics. Sometimes it worked and sometimes not.

The Audette ladder was for finding such a load, not for "developing" a load. I have run the Audete ladder with numerous rifles that already had an accurate load worked up (using the incremental test method) to find if the "ladder" would point to that load. Never found a single instance it did. However, the Audette ladder test would do as he developed it for at a specific long range, preferably 300 yards +.

I suggest you try the tried and true incremental load development method as it will save you time and components. Unfortunately some are now calling the incremental load development method a "ladder test" which it is not.

[Outpost75]

Larry's description of the ladder test is correct.

I was told by Col. E.H. Harrison that the concept was developed in the 1950s by Larry Moore and William C. Davis, Jr. at the Frankford Arsenal. The objective was to determine the best mean charge for machine loading cal. .30 M72 Match ammunition, which would produce the minimum 600-yard vertical dispersion in the M1 rifle for competition shooting, given the normal charge variation inherent in the loading machinery. The WW2-era plate loading machines commonly resulted in a variation of +/-0.5 grain with IMR4895.

[georgerkahn]

Mr. Audette was a frequent contributor to the olllld Precision Shooting magazine series, and I recall reading his writings, and discussions, re the Ladder Test. "Back in the day", the magazine had no dedicated or featured articles, buy mainly (e.g. 95%!) was just the printing and publishing of letters written back and forth by shooters at the top of their game. I probably have well over 100 issues -- and will, over next week or two -- look for the Ladder letters/reports. Upon finding them -- I'll advise. To me, at the time, they were very well worth reading!
geo

[Land Owner]

"Incremental Load Work Up - Audette Method":

[Land Owner]

I test one bullet "incrementally", 3-shot groups, in 0.5 grain powder charge weight increases to start. I get an "accuracy curve" that when plotted looks THEORETICALLY like this:





Powder charge (in grains) on the "X" axis and measured 3-shot pattern size (in inches) on the "Y" axis.

At the "relative minimum" powder charge of 38 grains, I load 3-shot groups in 0.1 grain increments toward 38.5 grains. I find the "true" 0.72" minimum group at the powder charge is 38.3 grains.

In this method I use the Mfg's published minimum and maximum powder charges. Often, this range is short, say 5.0 grains (or less) in total from min to max. Five grains times 2 (0.5 grain increments) times 3 shots is 30 rounds. Four groups times 3 shots (at 0.1 grain powder increment) is 12 more rounds for a total of 42 rounds to determine that powder's best group for my barrel.

After the "best group" powder charge is found, then I load at that charge in one manufacturer's, equal weight, neck reamed, neck sized, fire formed cases from that rifle's chamber, and adjust bullet embedment in the case neck by increments of 0.002" in 3-shot groups again to determine the BEST group by bullet jump to lands.

[Land Owner]

Things accomplished in shooting ~75 rounds of ammo through your rifle for a single powder in a one bullet accuracy test include familiarity with your rifle, confidence in your techniques - both reloading and shooting, visible results, and a confidence that when you put your reticle on a game animal or target, the bullet is going to go where you aim.

Aim small - miss small.

[Hossfly]

I do this the same as land owner, and once you know what it will do with that freebore your next trial you can seat boolits at that free bore. It’s mostly how that barrel harmonics play when that particular boolit exits the muzzle.

[JBinMN]

Maybe this link will be helpful to the OP:
http://www.mssblog.com/2018/02/22/re...-load-work-up/


The pic above below comes from the article. IMO< of course, it is a reasonable example of how tracking the shots as one progresses thru the testing, can give a good idea of what that particular firearm, in that environment, using a particular range for the firearm test, with all the components of the round the same, except the powder weight and keeping as many variable/factors the same as one can, a "sweet spot" for accuracy can be found for the load.
In the pic as one can see, as the powder gets into the range of 25.2 - 25.5 the groups tighten up with group 5 thru 8.


Some might adjust sights or optics to meet that load & range with that much testing, & others might then go on to do the same testing using 5 rounds per powder charge weight & perhaps reducing the incremental amount of powder weight to a smaller amount each time, but only working in the range of the best groups.

In the case of the pic shown, I would likely start at 25gr. & work up in small .1 or .2 grain increments/"steps" to narrow the load down to the best one. ( Some here would only go with larger increments, maybe just .03 gr. & call it good enough, but I am pretty picky about such things & enjoy such testing, so I have more fun & make the increments smaller.)

I call those "increments", "steps", regardless if other, more experienced folks here may not...

To "me", they are "steps" in a "ladder" of powder charge weights, with the lowest charge weight being the first step in the ladder & the highest powder charge weight being the top step of the ladder to reach the goal of finding the "sweet spot" in that particular firearm , at that range, in those particular environment, using those particular components.

Even looking at the shots in the pic, it can remind someone of climbing a ladder of shots up the target using increments or "steps" going up as one progresses...

Until I see someone define these tests & terms in a better way, "I' think I will call it a "ladder test".

Everyone else can suit themselves. They often do & it shows.


P.S. - I even do this with handguns, contrary to others here. Once again, suit yourselves...

[Larry Gibson]

JBinMN's example is much better as 3 shots with each increment of powder was used. The chronograph results of such an initial test can also quickly narrow down the efficient burning range of that powder in that rifle with those bullets. That way you can quickly narrow the 5 - 10 shot group testing down to a narrow range where the "sweet spot" will most likely be.

[Land Owner]

LarryG - JBinMN's chart (from the article) is rotated 90 degrees, marks where each round of the 3-shot pattern hits, and is the same information as the post #9 "theoretical" chart, whereas post #9 just measures and reports the spread of the 3-shot pattern. They are the same information displayed differently.

[David2011]

My favorite method of ladder testing is to load 5 rounds each at 0.5 grain intervals starting at the minimum recommended load to the maximum listed load. Depending on the firearm and load they may not all be shot. If the groups start opening up or there are pressure signs I stop.

I shoot the test through the chronograph watching the velocity and paying attention to the primers and bolt lift if applicable. I feel like 5 shot groups are more useful than 3 shot groups. That gives me an idea of the range of loads producing the best accuracy. I then work in a much narrower range with 0.2 grain intervals for the best accuracy.

[Larry Gibson]

Land Owner

My bad in not mentioning your post also as a much better way (using 3 shots of each increment also) to conduct and initial incremental test than with just 1 shot in each increment. The results are the same and gets you to the right range for further testing quicker. It also lets us see if the combination of components isn't compatible with the firearm and thus avoid further testing.

[Larry Gibson]

"My favorite method of ladder testing is to load 5 rounds each at 0.5 grain intervals starting at the minimum recommended load to the maximum listed load"

To us old guys who have been doing so for many, many years that is the description of an increment load test.......sometimes called an Incremental Load Development (ICD) test. The substitution of "ladder" (a term coined for the Audette test) is not correct terminology because it references the Audette method which is not used for regular load development but for a specific load at a specific range. Conducting and ICD is a completely different process than conducting an Audette "ladder" test for different reasons.....apples and oranges so to speak.

Check any of the old, and even the new, manuals and you will not find the use of a single shot "ladder" test recommended (or even mentioned) for load development. I'm not singling you out here and mean no criticism just trying to correct the misuse of the word "ladder". It is only with the advent of the internet where "experts" who don't know the correct terminology use many words incorrectly.

[David2011]

Larry,

Definitely mea culpa. I can’t blame the Internet; I was told that was what a ladder test was by an old shooter long before the Internet came along. I’ve been loading for about 40 years myself. I just didn’t know it was wrong. After reading about the Audette ladder concept I understand that it’s a way to test the harmonics of a rifle. Thanks for the clarification.

[osteodoc08]

JBinMN has the best illustration of a true ladder test. I've used this on occasion but typically shoot the incremental load development at 200 yards and then select the few nodes with the lowest standard deviation (SD) and Smallest groups and reach out to 300. Using SD to guide selection is also another way to narrow down the best load. I find this really determines the best efficiency for that powder and bullet combo.