Does anyone use ladder testing to determine seating depth?

[milrifle]

I was reading up on ladder testing and found an article where the author said you could use ladder testing to determine the best seating depth and best primer, but didn't give any details. He just concentrated on powder charge and only mentioned the other in passing. I can easily see how a string of increasing powder charges will result in a string of higher POI's. But will varying seating depth or primers really result in enough change in velocity to form a 'ladder'? Any of you guys ever given this a try?

[Love Life]

Ladder the powder charge. Shoot for groups using "THE" load (established during the powder ladder) varying seating depth. Once you have the best group from that, then you can experiment with primers over a chronograph.

[shooter93]

My experience with it...and I'm not knocking it....is...200 yards is much better than 100 for flat shooting guns. And you need a very good shooting rifle to start with. Doesn't seem to save any time or work with a great number of average rifles, the shot dispersion never seems to really "tell" you anything. Creigton Audette is given credit for it's development so Google him and I'm sure you'll find a complete description of the process.

[GP100man]

I never leave a powder until I`ve moved the boolit or bullet several times .

Then there`s charge weight , different primers , different cases .

But most always find a working load by adjusting seating depth.

[Love Life]

My first powder ladder is at 300 yds. My second ladder is at 400 Yds. I usually shoot a 3rd ladder, but that is not 100% necessary.

In my ladders I shoot every load with the bullet "Jammed."

once I have a happy spot with my powder ladders then I start tweaking seating depth.

Primer is the last thing I fool with.

The best and easiest description (with pictures and everything) of the ladder is on Sniper's Hide.

[Kull]

If I do seating depth ladder tests I do it first, before finalizing on a powder load. In my experience seating depth makes a bigger change in group size. I really don't think it makes a huge difference which one you start with just don't change both at the same time.

[Doc Highwall]

What ladder testing does, is it takes into account barrel vibrations to see where the bullets start to cluster. I learned about this a long time ago from Creighton Audette. Here is some information about it.

http://www.desertsharpshooters.com/manuals/incredload.pdf

[warf73]

I ladder my powder (lowest powder charge listed for that powder) using standard book call out OAL. The charge with the smallest group gets ladders with OAL being moved -.015 from standard to + .015". All load testing is done with 5 round groups at 100 yards.

My results have only been tested with J words on 17Rem, 204Ruger, 22-250, 243win, 25-06, 7mm-08, 308win, 30-06, 300wby, 460wby.

[milrifle]

Warf73,

How much difference in elevation do you see in a 30-06 at 100 yds when varying OAL?

[guninhand]

How bad has the wind got to be before you call off a ladder test?

[Love Life]

Depends how fast and how far you are shooting. In the ladder you are not making wind calls. You are looking for vertical dispersion. If the wind is blowing hard enough to move your POI off the target then that is to windy...

Warf-Are you shooting 5 rd groups of each powder charge?

[warf73]

How much difference in elevation do you see in a 30-06 at 100 yds when varying OAL?
At 100 yards I've never really noticed any as I'm shooting for group size. What I did see was the groups get bigger or smaller as the OAL changes.


How bad has the wind got to be before you call off a ladder test?
I live in Kansas anything under 10mph is rare, when load testing anything lighter than 7mm I try to shoot closer to 5 or less if possible early mornings seem best around here.

Warf-Are you shooting 5 rd groups of each powder charge?
Yes sir, I could probly get away with 3 round groups but 5 seem to show more about the load.

When load devoloping the 460wby I did use 5 shot groups for the 300gr and 350gr bullets. On the 500grs bullets I did use 3 shot groups as the beating I was taking with 3 was enough.

[44man]

Not a ladder test with depth. A friend wanted me to work a load but only had a small amount of bullets so I picked one charge and just changed seating depths. Groups were so different from one to another but I got to 1/2" with one.
Trouble was they are too long to fit the short magazine He does not hunt so he has no problem loading single shot.

[snuffy]

The only ladder test I ever used was to stand it against the barn, jump on it to see if it fell apart!:kidding:[smilie=1:

I just never could wrap my mind around the validity of that method. For one, you have to track each and every shot. AS YOU SHOOT THEM! (Expensive spotting scope). Two, you have to have a very stable bench and spend some money on a good rest and bags. Three, good shooting conditions. Four, having a range with no interruptions, like a curious bystander to interrupt your session-------. Five, a target stand that will not move in the wind. No off the hood of a car, or over a rolled up jacket. Six, a rifle that has inherent accuracy. Meaning it can shoot good groups with either factory rounds, or good handloads. Seven, a good scope of high enough power to see the aiming point clearly. My way of saying it is; if the scope didn't cost about what the rifle cost, then you don't have a good enough scope.

Here's a discussion over on the AR forum;

http://forums.accuratereloading.com/eve/forums/a/tpc/f/2511043/m/4661024271?r=5771015271#5771015271

Especially Larry Gibson's take on it;

Audeette was a match shooter who was looking for an easy way to find accuracy when loading his .300 Win Mag dispensing IMR 4350 with an accuracy of about 1.5 gr +/- with an automatic dispenser. His "ladder method" showed good results when loading for one specific range only.

Unfortunately pundits would have us believe it is the end all method for general load development. It is not. I fell for the pundits BS and worked the "ladder" every which way from sunday with several different rifles and cartridges. It only worked at the one specific range tested at, just as Audette developed it for. The ladder method of load development was a total waste of time and componants for general load development.

For general load evelopment for across a broad spectrum of ranges. I t does you no good to find a "sweet spot" where a 1.5+/- variation will hit close together at one range (usually 100 yards with the "believers).

Reason is even though those shots may hit close together with such a wide variation in velocity at one range the velocity ES will eat you up with large bullet drop at longer ranges. Most also do not consider the cone of fire. Unless you have a sub 1/2 moa rifle/load (if so then why are you working up a load?) random dispersion within the cone of fire each charge is capable of will skew the results.

Fact is there is not short cut to an accurate load. Start with quality compoants, use known data and work up the traditional way will get you there with much less effort. Start 3 shot test strings over a chronograph to get you where you should be velocity wise while watching for pressure signs. With a smaller range of velocity that looks promising you can then tweak the load +/- by .1 - .5 gr using 7 - 10 shot test strings for velocity consistency (low ES) and group size.

BTW; 3-5 shot test strings are not statistically sound. Best to use 7 - 10 shot test strings when tweaking the load. Also remember that the accuracy capability of your rifle/load is not the "average" group size. The cone of fire and accuracy capability is actually the largest group size you fire with say 5 three shot groups, 3 five shot groups or best is 2 or 3 ten shot groups. If using a big game rifle the cone of fire (accuracy capability) is where ten 1st shots go when fired at the same target on different days from different positions.

Larry Gibson

Then there's Dan Newberrys bastardization of the Audeette method called OCW, Optimum Charge Weight;

http://optimalchargeweight.embarqspace.com/

Do whatever you want, it's still a somewhat free country. To me, it's a waste of hard to get components.

[Love Life]

I shoot for zero at 100 yards, then don't shoot there again. I have a load for the 308 that is MOA to .75 MOA at 100 yds, but has printed numerous sub quarter MOA groups at 300 and consistantly rings steel out to 1,000 yds. In my shooting, and I do not claim to be an expert as I have learned alot from people here who can (in all probability) shoot circles arounf me.

I do not find the ladder to be a waste of time, for me, but I stick to one bullet and charge and practice with it non stop. One of the few things I have seen that directly translates from 100 yds to greater distances is round groups, and flyers.

I am always learning though, so I very much appreciate and enjoy these threads.

[milrifle]

Interesting links Snuffy. Certainly something to think about.

[Doc Highwall]

Years ago when I was talking to Creighton Audette about the ladder testing, he explained to me that he used a known powder like IMR 4895 with Sierra Match Kings and RWS primers. He would take and weigh his cases to keep the weight as uniform as possible so only the powder was the variable. He also had access to laboratory scales for the weighing of all the components that he used for the tests.

He would do the testing at 600 yards in the prone position with a sling and put a sand bag under his left hand. Somebody would be in the pits to mark each shot as it was fired, and this was done first thing in the morning when there was as little wind as possible.

Creighton Audette held a High Masters classification and knew how to shoot and did his own gunsmithing.

What the ladder test does at 600 yards that a chronograph will not do, is it takes into consideration the barrel vibrations with the bullet impact showing up on the target. I feel if you do the ladder test at the farthest distance that you will shoot it at like 600 yards, that the results will be valid. Trying to do the ladder test at 100 yards and then shoot it at 300 yards or farther is useless.

Shooting past 600 yards gets you into where the bullets can become subsonic, usually between 900 and 1000 yards and for that you will need to know your muzzle velocity and bullets ballistic coefficient to know what to do to keep it above the speed of sound.

[Love Life]

Not the nodes!!!

[country gent]

I have used the ladder method successfully in the past. When my wife was alive she would load each round .2 grn increments and one of the kids would "ferry" it out to me on the line. I would then shoot it at 200 yds and plot it. This worked really good as we didnt have any "extra" ammo left over after the test. We found loads that perfomed very well in all our rifles for a given caliber.
I have seen loads worked up and tested at 200 yds that fell apart at 600 yds on out. When ever possible I would test at 300 yds as close to how the rifle was shot as possible. Service and NRA Match rifles were tested prone with sling / cuff and sand bagged foreward hand. I also used my heavy shootiong coat and glove. This worked better for me than the benches did. Rifle shot using heavy sling tension may have a diffrent point of impact to point of aim due to position/ tensions.
I believe its not so important the testing method as doing everything consistently and as close to how the rifle is normmally used as possible. Change only one thing at a time, work in a standard direction, have a goal set before starting, keep good notes and detailed information.

[warf73]

I'll stick with my way of loading since I don't comp. shoot and only shoot for meat, or varmite shoot. I know it works for my needs and while testing your getting trigger time.

[Doc Highwall]

I agree with what you said country gent.

[Larry Gibson]

Doc's description of what Audette's "Ladder" was used for by Audete is correct. Addtionally Audette developed the method because he was using an automatic powder dispecer that would throw +/- charges that were not as consistent with a manual thrower or with weighing each charge. The Ladder test was developed to show where the best accuracy was within a +/- range of charges the automatic thrower would dispence at long distance (the minimum he used was 300 yards but prefered 600 as mentioned). I am constantly amazed at how Audette's Ladder is bastardized into every means of load development for which it is not intended.

Yes I have extensively tested Audette's Ladder with multiple rifle/cartridges at 100 - 600 yards and understand it's limitations. How anyone using the Ladder outside of the very narrow parameters where it actually works and expects one shot of one load to realistically tell them anything about the quality and consistency of that load is beyond all understanding. There are no shortcuts (what most want in using the "Ladder") to proper load development.

Larry Gibson

[snuffy]

I'll stick with my way of loading since I don't comp. shoot and only shoot for meat, or varmite shoot. I know it works for my needs and while testing your getting trigger time.

EXACTLY

I'm 67, I started loading when I was 22. I'm not about to change to some new idea at this late date. Furthermore, I don't have bench rest quality rifles, just factory stuff or milsurp.

Optimal charge weight technique springs from the belief that there's some magical "BEST" powder charge/load that will shoot really well in all rifles. They point at the Federal gold medal loads in .308 with the match HP's. They seem to shoot better, but it's mostly the match bullet from sierra.

I'm fussy about a lot of things pertaining to loading. It's why I'll try new things for casting like building a PID for temp control and switching to MP custom molds for some boolits. BUT I'll gladly settle for 1" groups from my factory rifles, and 2-3" groups from my milsrup 03-A3, mosin, and mauser rifles. The barrels are pretty pitted, and stock sights are hard for this old man's eyes to sight accurately.

I sometimes wonder if some people are thinking the Audette OR OCW will turn a factory rifle into a benchrest quality rifle. It won't happen! Spend a bunch of money with the right gunsmith who knows how to blueprint a remmy 700 action, get a great barrel in heavy contour, have it chambered in .308, 6mm BR or another of the already established BR calibers. THEN do the Audette ladder, or the OCW, you might get a consistent load that will perform at all distances.

[Love Life]

Legit.

You have to ignore the Tasco scope on there. I was torture testing it, and found it to be an outstanding scope, but that is a write up for another time.

[milrifle]

I'm thinking the ladder test will give you a better idea for where to do some more in depth testing. But I'm thinking powder charge only. I don't see how it would lend itself very well to testing seating depth or primers.

[jonp]

At 100 yards I've never really noticed any as I'm shooting for group size. What I did see was the groups get bigger or smaller as the OAL changes.


I live in Kansas anything under 10mph is rare, when load testing anything lighter than 7mm I try to shoot closer to 5 or less if possible early mornings seem best around here.

Yes sir, I could probly get away with 3 round groups but 5 seem to show more about the load.

When load devoloping the 460wby I did use 5 shot groups for the 300gr and 350gr bullets. On the 500grs bullets I did use 3 shot groups as the beating I was taking with 3 was enough.

I can think of a bunch of things I'd rather do than load test a 460 Weatherby. In fact, just about anything. Hats off to you for that

[btroj]

Like Larry said, the ladder test was developed to find a powder charge, or range of charges, where a small difference in powder charge showed minimal difference on the target.
Think of it this way. 22.0 gr impacts 1 in low. 22.5 is dead on. 23.0 in 1/2 in high. 23.5 is 5/8 in high. 24.0 is 1 in high.
Go with the 23.0 to 23.5 gr charge as it doesn't make much difference on paper ifmitmis 23.0 or 23.5 gr. it allows for small errors in powder charge.

The ladder test isn't intended to be used for anything else.

I never used it personally. Got a second upper for highpower and just used the same charge. Made small changes to seating depth and it was just fine. Shot great at 600 so why burn a barrel up in testing?

[Doc Highwall]

Actually very few shots are fired with the ladder test. Say you want to shoot your favorite powder IMR 4895 in your 308 Winchester, and the powder charge that you see in the loading manual starts at 38 grains and ends at 41.5 grains max. So you first make a few rounds loaded with 39.0 to 40 grains just to get on paper with your sight settings. After you are satisfied that you can keep all your shots on the target you now load just 20 rounds where the cases all weigh the same with the powder charge as the only variable. Because you want to end up at 41.0 grains max you start with the first case loaded at 39.0 grs., the second at 39.1 grs., the third at 39.2 grs. until you get to the max of 41.0 grs.

Now the day you go out to test this has to have as calm of a wind condition that you have in your area. The target has to be set up with somebody in the pits ( A cell phone will help) and ONLY ONE AIMING POINT is used for the test. As each shot is fired the target is pulled into the pits and the shot marked with a number 1 –20 that corresponds to each .1 grain load starting with 39.0 grs. being 1, 40.0 grs. being 10 etc.

After the 20 shots have been shot and numbered you look for patterns in bullet impact where elevation on the target is minimal, over say a .4 –.5 grain powder charge variation. Your sweet spot for your powder charge will as close to the middle as you can get.

[btroj]

Exactly Doc. And it is best done at a good range so the impact variations are obvious. 100 yard ain't gonna do it.

[Larry Gibson]

Another thing that many do not consider even when using the Ladder correctly (as Doc explains) for the intended purpose (as btroj explains) is cone of fire. Audette was using extremely accurate match rifles capable of 1/2 moa accuracy for 20+ shots. With such on shot of a specific cartridge will work. However, with a 1+ moa rifle (20+ shots and how many sporters or milsurps can really do 1 moa or even 2 moa?) you have to understand how random dispersion within the cone of fire at 300 - 600 yards can give a false indication of "grouping". To work you have to shoot a group of sufficient shots and use the center of the group but then that's exactly like the standard method of working up a load, isn't it......it also uses the same or more shots. You can move the target closer than 300 yards but that defeats the purpose of the test and results are not really conclusive. Some may think they are but in reality they are not.

Bottom line is you may think the Ladder works for load development of all kinds but in the end you will shoot the same number of shots or more (been there done that) to "tweak" or verify a load. You may also find the load selected based on the Ladder test is way below the cartridges potential and what you bought it for (been there done that also). In the end you are far better off in load development to use standard practices which have developed over a long time and are proven. There are no short cuts to load development which is what most want fromthe Ladder test.

Larry Gibson

[btroj]

Good point Larry. Audette was testing very accurate rifles designed for competition.

Ladder testing is a very specialized tool. It was designed for, and is best left to, the realm of long range competition. Long range as in starting at 600 yards.

[Doc Highwall]

For people who have only a 100 yard range and a chronograph a different test is much more appropriate. Get as many cases 80 to 100 from one lot that weigh within 1.0 grain max., now with a powder that you have used in your rifle starting 10% below max and work back up in 1% increments.

Example 50 grains will be your max charge, minus 10% = 5 grains meaning you will start at 45.0 grains with your powder charge. Now 5 grains represents 10% so .5 grains represents 1%.

Now load just 5 cases with each 1% starting at 45.0 grains, 5 cases with 45.5 grains, 5 cases with 46.0 grains etc. and place them in your loading block/case holder in a order that you can shoot them with out mixing them up.

Take a separate target for each 5 shot group and mark it with all the load data,data weather conditions etc. This is a lot of work but it will be well worth it after you get done.

Set up your chronograph and target at 100 yards with two targets max one above the other so you only have to make a elevation adjustment with your front rest or rear bag. The object is to shoot slow with short rests in between changing each 2 targets. After all 55 shots are fired comes the time for evaluating the data you just collected.

First make a chart to plot out each 1% increase in powder charge, now look and if you see a flat point on the chart where the velocity gain is very little, you will also see other spots where you will get a significant increase in velocity. The flat spot between two of the 1% powder charges is going to be the best powder charge for your gun. Measure each 5 shot group for each 1% measuring just vertical and horizontal and record that as well and compare it to your plotting chart of 1% powder charges.

For the test I would start with the bullet touching the lands so there is only one way to go, backing off the lands in say .005” steps. Now that you have a real good place to start with your powder charge say it was between 48.0 and 48.5 grains so now load all the cases with a powder charge of 48.2 –48.3 grains (I know as close as you can) and load 10- 15 with the bullets touching the lands, another 10-15 .005” off the lands, and continue in this manor.

In the first part you learned that a powder charge between 48.0 – 48.5 grains did not affect bullet velocity as much as other 1% variations and is the starting point. The second part is for bullet seating depth as the only variable. Now you can shoot 5 shot groups or just use 5 shots to make sure the groups is centered on the target and then shoot a 10 shot group or even shoot 2 7 shot groups.

After you find out what the gun likes for how far the bullets are in relation to the lands you can even go back and load a small lot of cases in +/- 1% on either side of the powder charge and seating depth you found best in the first two tests.

Keep good notes of every thing you do and it will pay for itself ten fold in the end. It will take one day to weigh the cases and get them within the 1 grain max and weigh the powder charges and load for this test. Then it will take one more day to do the shooting and plotting, and one more for the seating depth test. Spending time on three trips to the range for doing this along with the time for setting it up is a small price to find out what makes your gun shoot the best, and the satisfaction of beating some one with a average looking gun will make you smile inside.

The first time I did this with a Remington 40X in 222 Rem. with a shot out barrel, I was using IMR-4198 powder with a charge of 19.7 grains with a Sierra 55 gr. FB. I was able to make the gun go from shooting 1 minuet of angle to under one half minuet of angle for 10 shots at 200 yards, and I only had about .050” – .060” of the base of the bullet in the case mouth.

You do not need a target rifle to do this test, you only need the desire to get the satisfaction out of doing the best with what you have.

[Love Life]

I'll post more pictures later, but in the ladder test I only use one powder. Moving up in .5 gr increments using BLC-2 I start at 41.0 gr and stopped at 47.0 gr.

Within that charge range there was over 12 inches of vertical dispersion with the "nodes" being within 41-42.5 gr, 43.5-44.5 gr, and 46-46.5 gr at 300 yds.

The missing numbers were the charges where the shot was not within the "node"

Due to needing horsepower to push the 175 SMK out to 1,000 yds I ignored the lower end. From there I shot another ladder moving up in .3 gr increments with the 43.5-44.5 and the 46-46.5 gr ranges at 500 yds.

44.0 gr and 46.0 gr were my best. Both loads are sub MOA out 600 yds (under 6 inches with MOA being 1.047 and rounded down). Now keep in mind I only used one powder, and only varied the charged. Once you have a load that satisfies you then you can play with primers and seating depth.

Tula LRM primers give me the most consistency and using a bullet comparator to sort my bullets, my rifle likes to shoot with the bullet "Jammed."

Now my rifle is a FN-SPR A5M in 308 Winchester. I use t for long range song dog slaying and tactical (barf) long range matches. I have seen benchrest shooters in action and their bad rifles/groups would be sources of pride for me!!

To answer the OP: When ladder testing only vary powder charge. This is also one o those times where you completely ignore windcalls.