Ladder technique mystique

15 April 2004, 15:37

voldoc02

Would someone please explain the ladder technique of load developement.. thanks, Doc Stone :

15 April 2004, 16:09

denton

There are a couple of people that will probably chime in with more knowledge than mine, but here is the basic idea.

As the bullet exits the muzzle, it will be deflected by the sideways-up and down vibration of the barrel. If all bullets had exactly equal transit times down the barrel, it would not matter where in the arc they exit. Since this isn't usually true, but it is usually true that bullets that exit at or near the end of the arc will be more consistent in their grouping.

Variation is a slippery devil to pin down, and group size is variation. It takes a lot of groups to determine how accurate a rifle is. So checking your group sizes is a slow, difficult way to improve accuracy.

A better approach is to set up something like half a dozen targets, and shoot at them with six different loads, perhaps half a grain apart in load. Shoot the various loads in random order, but shoot all the lowest loads at the first target, next lowest loads at the second target, etc. (ooops... before you start, a couple of fouling shots to warm the barrel... shoot slowly, attempting to keep the barrel at a constant temperature).

Finally, locate the center of all the groups you have shot. The 2-3 groups that center closest to the same point on the target represent your most accurate load.

The clever thing about this is that it transforms the problem from comparing group sizes, which is difficult (3:1 ratio in size does not indicate change), to measuring POI, which is relatively easy.

The physics and stats add up nicely. The problem is that 15 degrees F difference in barrel temperature easily exceeds the effect of adding another grain of powder. Still, it will probably help you find accurate loads for your rifle, expending no more than about 40 rounds or so.

15 April 2004, 16:21

voldoc02

Thanks for the great effort but maybe I need a book or an article to read...???? Maybe I can figure it out later.. thanks and feel free to expand , anyone.., thanks, Doc Stone

I may be a dumbA$$

15 April 2004, 18:14

Paul5388

Someone posted this on the "Ladder Method" thread a few days ago.
web page

16 April 2004, 00:52

voldoc02

Thanks Paul, I've read the article now and am beginning to see the light at the end of the ---..target?? ha.. anyway great link and again thanx, Doc Stone

16 April 2004, 03:14

Hot Core

Quote:

There are a couple of people that will probably chime in with more knowledge than mine...

As the bullet exits the muzzle, it will be deflected by the sideways-up and down vibration of the barrel.
...
A better approach is to set up something like half a dozen targets, and shoot at them with six different loads, perhaps half a grain apart in load. Shoot the various loads in random order, but shoot all the lowest loads at the first target, next lowest loads at the second target, etc. ...

Hey Doc, Always nice to be able to agree with someone. Denton was absolutely correct with his first statement.

Due to the various forces acting on the barrel and bullet during the firing sequence, it is much easier to understand Mr. Creighton Audette's Method (Ladder) if you simply imagine the muzzle moving in an elongated figure " 8 " pattern. It might be skewed slightly right or left, but basically there are forces created during the Firing Sequence sufficient to create this movement.

The trick in Load Development is adjusting the Load so the Bullet exits the muzzle at either the Apogee or Perigee. This is because the muzzle is making the least movement then. As it is crossing the middle of the " 8 ", the muzzle is moving at it's highest speed.

...

Denton goes on to partially explain the fiasco devised by a Rookie who thought he was bettering the Audette Method. No slam on Denton, it just isn't the Audette Method. And the Rookie Green Fiasco has degraded the potential of the Audette Method considerably.

In the Audette Method you load a series of Test Cartridges with some variance in Powder between "each" cartridge, shoot them at a single target placed 300yds out, notice and record each specific shot per it's Load, and then look for clusters of shots.

For example, you would load 223Rem Test Loads perhaps 0.2gr apart, 308Win - 0.3gr apart and 300WinMag - 0.5gr apart. The idea of shooting them at 300yds is to make the clustering more apparent and you may see two clusters in a test.

One thing Rookie Green was correct about is there are cartridges where shooting at 300yds is impractical. Cartridges of low Velocity such as a 30-30, 35Rem, 444Mar need to be shot at a closer distance, but far enough to spread the shots, maybe 150yds.

The "Round Robin" portion of Rookie Green's Fiasco is one of it's biggest goofs. Spreading the shots over an increased amount of time allows the wind variable to have increased influence on the groups. The best idea is to shoot as many shots as practicle, as quickly as possible, "without overheating the barrel". This is so the wind condition is as nearly the same as possible. I like to do Mr. Audette's Method at either sunrise or sunset since the wind tends to calm for a short period.

Once you locate the clusters, then reshoot those loads in groups of 3-shots. For example using the 223Rem, if you determined 2x.0gr, 2x.2gr, 2x.4gr and 2x.6gr single shots formed a cluster, reload 3 of each and then shoot on separate targets. Hopefully you will find that a Load near 2x.5gr provides the best balance. Locating the central Load for a cluster provides the best opportunity for your Final Load to be consistently accurate.

Then reshoot and adjust the Seating Depth to "Fine Tune" the Final Load.

Nothing complex about Mr. Audette's Method which is one of it's great strengths.

16 April 2004, 04:03

voldoc02

Hotcore., I now understand the technique.. thanks to you guys.. My problen is I don't have a place to shoot 300yds. off a bench.. Would 100yds. or 200 yds. be acceptable?? advise and expand:, you guys are great. By the way do you need any info on dentistry?? (I don't think so) ,Doc Stone

16 April 2004, 04:49

beemanbeme

Doc, the distance is incidental. You can use 173.5 yards if you like. The idea of the greater distance is to make the shot pattern clearer. If I were to use the ladder method at 100 yards with my 22-250, I'd get a large ragged hole that would be elongated up and down and it would be very hard (impossible???) to determine where the shot cluster was. I believe the original method used a very tall narrow target with one aiming point. The shots would kinda wander up the target as greater powder charges were used. At some point, a few of the shots would fall closer together (cluster). That is the "sweet spot" for that powder. Now then, you reload shells using the cluster as the powder bracket and use smaller increments of powder and repeat the shooting part of it. And so forth. Then someone tells you, "you've got to try some xxx powder in that cartridge. Its much better than the one you're using." Then you get to start all over again.

16 April 2004, 05:56

Turok

Quote:

My problen is I don't have a place to shoot 300yds. off a bench.. Would 100yds. or 200 yds. be acceptable??

That is the greatest weakness of the Audette Method, most of us just don't have the distance to make good use of it. That's also the greatest advantage of the Optimum Charge Weight slammed by HotCore in his personal attack against the creator (unfortunately it's a common occurance with HC

).

As already mentioned, the Audette method will provide you with little more than a shotgun pattern at the shorter ranges. In order to really see the barrel harmonics at play, you need the longer ranges. In this case, the longer the better.

On the other hand, as Denton pointed out, OCW provides the shooter with a statistically sound shooting method that can be utilized at distances as short as 100 yards. If you have longer ranges available, great. If not, it's still works great.

You can check out the OCW method at http://www.clik.to/optimalchargeweight

I encourage you to give both a try and see which way to skin the cat works for you.

Turok

16 April 2004, 14:20

Hot Core

Quote:

... Would 100yds. or 200 yds. be acceptable?? ...

Hey Doc, beemanbeme gave an excellent answer, so there is no need for me to go into great detail about your question. He is absolutely correct that a Flat Shooting Cartridge will usually "hide" the clusters at 100yds.

If your cartridge is what we typically think of as a Flat Shooter, then the 300yds will make it easier for you to locate the grouping. 200yds can work, but as beemanbeme mentioned, it is just more difficult to see it.

It is a darn shame that most Ranges seem to be limited to 100yds and a person has to seek out one with a bit more distance. 100yds is fine for the real short range cartridges.

...

I didn't mention this before, but as you increase the Loads the string of shots "usually" rises on the Target at 300yds. If you look at the Trajectory Tables in the back of a Bullet Manufacturers Manual, it will be fairly easy to understand.

As we increase Powder at 100yds, the Point-of-Impact is often Lower than the previous shots. This is because we are shortening the barrel time. This causes the Bullet to exit the muzzle at a lower point in the Recoil Arc which is a completely different dynamic from the forces that cause the elongated figure " 8 ".

Now, since the Bullet is shooting "faster" the top of the Bullet's Trajectory is pushed farther away and slightly higher. Thus, the string of shots at 300yds typically move in an upward direction with a Flat Shooting cartridge.

Best of luck to you!

16 April 2004, 16:03

Curly

[quote...........As we increase Powder at 100yds, the Point-of-Impact is often Lower than the previous shots. This is because we are shortening the barrel time. This causes the Bullet to exit the muzzle at a lower point in the Recoil Arc which is a completely different dynamic from the forces that cause the elongated figure " 8 ".

Thanks Hot Core. I wondered why my .300WM would shoot lower at 100yds with my hotter loads.

16 April 2004, 18:28

500Mag

Of course heating up the barrel with additional shots works fine for target shooting but if you're using a gun for hunting your practice shots needs to be from a cold barrel to see how it's actully going to group in my opinion because the barrel is going to be cold when you make that first shot and the first shot is the one you really need to be on the money with. At the range I shoot one gun at a target and lay the gun aside and shoot something else for a while until it cools completely down and shoot again and so on to see if it's groups the same each time when cold. That's my 2 pennies worth for a hunting rifle or handgun.

5M

17 April 2004, 00:57

Tailgunner

It's a load development technique, not a sight-in technique, in fact the scope adjustments are not touched during the entire string. So having the barrel at a warm/consistant tempature, as opposed to cold, is not a issue.
Once the load is fully developed, than switching over to "one shot from cold" sight-in is the norm for hunting weapons.