Ladder Test Instructions
Click here to download a test
target in PDF format.
The ladder test is a technique used to develop the most accurate load for your rifle with only a few shots fired.
This method is also known as the "Audette Ladder Test". It's origination is widely attributed to Creighton Audette who evidently passed away at the age of 74 in the mid '90's. I would like to be able to expand upon Audette the man on this page. If you can provide me with any further information about the man please email me.
The advantages of using this system is that it is faster and more economical than the traditional method of load testing we are most familiar with and as presented in every issue of every shooting magazine on the rack.
To read the rifle mags, one would think that the only way to develop a load is to load dozens of variations of the same components and shoot hundreds of rounds downrange to obtain the best group average. This process is costly, time consuming and wears on the barrel. Frustration and costs usually end up causing the shooter to short cut the system by shooting one or two three shot groups and basing decisions on those few groups. Three shot groups look great on paper but the fact is that even the worst rifle and load will shoot a good three shot group occasionally. It's the positive side of Murphy's Law. “If it can happen, it will happen.”
Once this test is completed, the shooter has the option of sticking with the load arrived at or doing further variations to refine the results. It's up to the shooter and what the end goal is for the load. A shooter looking for a good hunting load will probably not need to do any further development. A match shooter may do considerable additional experimentation with different powders, primers and seating depths.
This load development system is only as good as the rifle being tested. If you have a bad bore, crown, lock up, bedding or loose sight mounts, you are wasting your time with load development until the problems are solved. On top of that, some rifles just don't shoot worth a darn no matter what you do with them.
Before proceeding with load development, read the instructions and satisfy yourself that you understand the procedures. Click one of the links at the top of this page to download the instructions in a text format or a PDF format. Especially the text file is best to downloaded rather than opened on your screen as it does not format well when opened directly.
Step 1, preparing the loads
A. Select the components you plan to test. Usually the most important component is the bullet, since this test is specific to the components tested and, generally, the shooter is looking for the most accurate load for a given bullet for a given purpose. Regardless of which test component is of the most interest to you, the results of the test are only valid for the components tested and for the loading procedure used for the test ammo.
Lets say you want to find the most accurate load for your .270 Winchester shooting the Nosler Partition 130 grain bullet.
B. Select a powder that has a reputation for good performance in the specific cartridge, in this case, the .270 Winchester. Without making any specific recommendation, 4831, 4350, R19, R22, W760, or WXR are all pretty good candidates and there are surely others. If you don't know what powder would be good in your particular cartridge, look through the loading manuals for a recommendation of a best accuracy powder.
C. Choose a primer based upon recommendations of the powder manufacturer. If a magnum is recommended, for example, then use it.
D. Select your case. Stay with the same manufacturer of cases and same lot number if possible. Size the cases, if previously fired, in the manner in which you plan to size after you have completed the test. In other words, if you plan to neck size only in your final load, then do so for the test. Regardless, treat all cases the same. Trim to length, chamfer inside and out and clean them prior to loading. If you have other steps that you typically perform in case prep, do them also. Uniformity is the word.
E. Prime the cases in your usual manner.
F. Charge the cases. This is an important step and needs to be done with as much precision as possible. First, determine the max charge for your combination of components by referring to your loading manual and then decide what will be your max charge for the test. I suggest that you select a max charge of no more than that recommended in your manual and further suggest that your max test charge should be a bit under the max charge in the manual. If you have already determined a max charge for your rifle with the test components, then use that as your max test charge. Remember, the purpose of this test is not to determine the max load. You are looking for the most accurate load. The powder charge in each case will be different and will increase in equal amounts up to the max charge weight. The difference in the charge weights will depend upon the case capacity of the cartridge being tested. For example, in small cases such as .223, the charge in each case can be increased in increments of 1/10 grain. In medium sized cases, the increment will be 2/10 of a grain and in larger cases 3/10 of a grain. These increments are not etched in stone. If you choose to test a small capacity case in 2/10 of a grain increments, no harm is done but it may lead to a less precise conclusion.
We are going to load twenty rounds for the test and each round will be identical except the powder charge will increase by the chosen increment with the last round being charged at your chosen max load. So, the difference between the first round and the last round will be 40/10 of a grain or 4 grains. Now, subtract 4.2 grains from the max charge and this will be your start load for round one.
How you determine the weight of each charge is important. My method is to set my powder measure to throw just under the weight of the first charge and then use a Hornady powder trickler to bring it up to exact weight in the pan of my balance beam scale. Remember that many electronic scales are accurate to within 1/10 of a grain according to the manufacturer. That means that a 50 grain by weight charge could vary 1/10 of a grain either way for a true weight range of 49.9 to 50.1 grains! For this reason it's best to use a balance beam scale.
Here's an example of the progression of charge weights. Lets say your are testing H4350 with your 130 grain bullet. Hodgdon suggests a max charge of 54.3 grains. However, from previous experience you know that your rifle should not exceed 53.3 grains. Or, you simply select 53.3 grains for safety reasons. In either case, 53.3 is the max charge. This load data is not a suggested load for the .270 Winchester. It is only an example of the process used in the test.
So, charge number one is 49.1 grains and each round will be increased by 2/10 of a grain. The last round will end up charged with 53.3 grains.
Each loaded round must be marked, labeled or packaged in order to retain the identity of each, numbered one through twenty. If you lose track of the numbers of any of the twenty rounds, the test will not be valid. You will be taking these twenty rounds to the range and firing them in numerical sequence. Firing them out of sequence will invalidate the test.
Step 2, At the Range.
A. Range conditions are very important to a successful test. Ideally there should be no wind whatsoever. Maybe a gentle breeze is ok if it is indeed gentle and, more importantly, steady and unchanging in velocity and direction. If range conditions don't meet this criteria, don't shoot the test! There will be no point to it. Analyzing the results will be difficult and misleading.
B. You can use any target for this project, but certain types are preferable. I prefer a large crosshair target that can be easily seen in the scope. Place your target on a large backer. The larger the better. Two feet square would be a good starting point and larger would be better. A piece of unmarked and clean cardboard with no holes in it is a good backer.
Center your target on the backer and place it at the distance you plan to shoot. The further the better! If you are testing a relatively accurate rifle with long range capability, then 200 yards is probably the minimum and 300 yards would be better. Accuracy is relative to calibers, type of rifle, etc. If you are testing a 30-30 that does not have a whole lot of inherent accuracy, then 100 or 150 yards will probably do fine. The same holds true for any caliber if it is not inherently a very accurate rifle. You will understand this better when you read the section on target analysis.
C. Now we are ready to shoot. You must shoot from a bench. If you don't have a bench, you may get by with a prone position off a bipod or some other solid position but as you proceed, you will see why a solid bench position is ideal. By solid bench position I mean forearm support and support at the toe of the butt as well. Using a bunny bag at the butt is ideal, but a sandbag or two will do by placing the butt on the bag and pushing the rifle forward or pulling it back to obtain vertical alignment with your target. Each and every shot must be fired as carefully as possible!
We don't care where we hit on the target as long as all the shots go into the backer and can be seen through your scope or a spotting scope. You should have a copy of your target on the bench next to you as you shoot. Start with your barrel cleaned and a few fouling shots fired. Don't use your test ammo for fouling shots and don't fire your fouling shots at your test target. As you shoot, let your barrel cool between shots and consider cleaning it thoroughly every four or five shots and remember to shoot a couple foulers after cleaning. We want to maintain the same barrel conditions for each shot as closely as possible.
Start with round number one and progress through all twenty rounds. After each shot, record the impact point on your duplicate target at the bench and number it. Your duplicate target should match the actual target as closely as possible and each hole in your duplicate target should bear the number of the round you shot it with.
As you shoot watch for pressure signs. If you see signs of pressure, stop! The test is over when you encounter pressure or have fired all twenty rounds.
Retrieve your target and, using your duplicate target, number each of the bullet holes in your target according to the corresponding numbers on your duplicate target. When you are finished numbering, all twenty shots should be accounted for and each should bear the actual number of the round that made the hole.
Step 3, Analysis
As you study your target, look for a tendency for consecutive shot numbers to group together. That grouping of consecutive rounds indicates a sweet spot for the components you are testing. If you have 3 or 4 or more shots clustered together, then that is a range of powder charge that will give you the best accuracy with the components tested. There could be a tendency for more than one cluster which could indicate more than one sweet spot. This cluster does not represent the group sizes that you will achieve using the results of the test. Remember, the cluster is made by a series of shots, all of which were slightly different. The key here is that all of those shots fell into a load range that is favored by the test gun.
At this point, you have pretty much arrived at your load range. Now you have several options. One is to select a charge weight that falls in the middle of your cluster and go with it. Another is to load another series of 20 rounds in smaller increments bracketing the charge weights that clustered together. For example, if you found that rounds 13 through 17 clustered closely, you might want to load a series of 20 rounds that take in the charge weights between rounds 10 and 20 using 1/10 grain increments. It just depends on how critical you are of your end results. Other options are to play with different primers and bullet seating depths.
When experimenting with primers and seating depths, it is probably a good idea to return to the conventional load testing methods. Load 10 rounds of each variation and shoot two five shot groups of each variation to see if there is any improvement.