Ladder test?

[Mulga]

Hi all. I have changed the way I do load development and have for the first time tried out a ladder test. I assume I'm meant to see points of impact tracking up the target, so how do I interpret this?

140 gr Barnes TTSX, 43.0 - 58.0 gr AR2209 (H4350) 10 shots, increasing in 0.5 increments shot at 100 metres. Fired from a Kimber MA .280AI. This rifle is new to me so some of the shots could be wiggle. Through the 8x I couldn't see much of what was going on but I know the highest hole is the hottest with 58gr; I thought I was off the paper for most of the shots until I walked up to it.

Cheers
Dan

 

[UtahJimmy]

Ladder tests are best fired at 200+, gives the bullets a little distance to separate. You should be noting where each one hits.

Does you no good if you don't know which holes are which charge.

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[Mulga]

Thanks. I will give it another go

 

[BradNSW]

When I did load development using the ladder method, I fired 5 shots at each load, using a bench rest. I used a new target for each 5 shots. Took all day at 200yd range.

What I judged was the size of the group. You're trying to find out what load harmonics the barrel holds the tightest groups at. Doesn't matter where it hits...you adjust the sights after picking a load.

Pretty amazing to get results like below:

63 - 1.4x1.6"
63.3 - 1.6x1.5"
63.6 - 1.1x1.3"
63. 9 - .9x1.0"
64.2 - .8x.7"
64.5 - 1.0x 1.2
64.8 - 1.2x1.0"

Then the next week, did 5 shots at .1gn increments from 63.9 to 64.4. Ended up with 64.1gr's holding the tightest group at 200yds. Then I zeroed my scope...

 

[doverpack12]

Looks like it’s shooting pretty well but a little further distance and knowing which shot corresponds to each charge will tell you more. From that target knowing a majority of the shots hit the same hole I might just start trying charges in the middle of the range depending on your end goal.

 

[N2TRKYS]

I'd be more interested in the velocity than where they hit or how far the target is. Once I got into the accuracy node, velocity wise, then I would shoot 3 rounds per powder charge in that node.

 

[bpotter]

Thanks. I will give it another go

Do a search on Dan Newberry OCW test. There are usually 2 nodes sometime 3.

First, you should find pressure with bullet and powder combo or make sure you don't see pressure signs at the upper book load combination for you powder and bullet. The latter usually is usually not a problem with modern mfg. rifles . A chronograph is helpful here as" too fast to be true velocities " mean you might be running to hot.

It's how I do it but not the only way.

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[tyeager2964]

Basically i see multiple powders creating the same vertical displacement which in your type of ladder test should indicate an accuracy node where you can be off by a little in your reloading and still hit the same POI.

As stated above most people run this type of ladder test at farther distances and some will use a sharper to color the bullets so they know which powder charge corresponds to which hole.

20 to 30 fps will not mean much at 100 yards or meters but should show up at 300 plus.

The 6.5 guys have a good YouTube video on this method but I forget the title. It was something like optimum charge weight in 10 rounds

It sounds like you have the basic idea but just need more distance to allow the small fps difference to disperse.

 

[BrushyHillGuide]

If you have somewhere that you can shoot your ladder at 400yds or even further the results much clearer. It’s meant to be shot at 400+. If you don’t have a place, Newberry’s OCW is a better method.


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[FURMAN]

If you have somewhere that you can shoot your ladder at 400yds or even further the results much clearer. It’s meant to be shot at 400+. If you don’t have a place, Newberry’s OCW is a better method.


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This is a fact. You are wasting your time shooting a ladder at less than 400. I would strongly suggest 600 or farther. If you do not have that available. You would be far better off with the OCW. The entire point of a ladder is to find the least vertical dispersion. You will get false data at a distance too short to have velocity effect vertical. When you get out to 600 plus velocity becomes a large factor in vertical dispersion. At 100 yards it will be less of a factor than the accuracy of the particular rifle.

All that target really tells you is that most likely your rifle is going to be a shooter. As far as what powder charge to use it is worthless.

If you want the best info on ladder testing look at this http://www.6mmbr.com/laddertest.html

if you do not have long range available look at this OCW Overview - Dan Newberry's OCW Load Development System

I have modified/simplified both my ladder and OCW testing but these will be a good read. I prefer the ladder as it will find the node with less shots.

 

[cowboy]

A lot of good info in the above comments. I will give you another option that is a modified ladder test based on velocity only. I have been doing a number of variations of different ladder type testing for close to 40+ years. Since the vast improvements and accuracy of chronographs in recent years I now just shoot over a chronograph (at any distance) with powder increased at .5 gr. There will be a node in there where the 2-3 velocities are very similar and in some cases a higher powder charge will actually run slightly less than a higher powder charge. This eliminates any human error or weather situations also.

 

[FURMAN]

A lot of good info in the above comments. I will give you another option that is a modified ladder test based on velocity only. I have been doing a number of variations of different ladder type testing for close to 40+ years. Since the vast improvements and accuracy of chronographs in recent years I now just shoot over a chronograph (at any distance) with powder increased at .5 gr. There will be a node in there where the 2-3 velocities are very similar and in some cases a higher powder charge will actually run slightly less than a higher powder charge. This eliminates any human error or weather situations also.

While I believe this works most of the time I have found with at least two different rifle/load combos that there are times when I get a particular load with very good es and sd over at least a grain powder charge change will not group at distance so I actually gave up on using a chrono during load development.

 

[BrushyHillGuide]

A lot of good info in the above comments. I will give you another option that is a modified ladder test based on velocity only. I have been doing a number of variations of different ladder type testing for close to 40+ years. Since the vast improvements and accuracy of chronographs in recent years I now just shoot over a chronograph (at any distance) with powder increased at .5 gr. There will be a node in there where the 2-3 velocities are very similar and in some cases a higher powder charge will actually run slightly less than a higher powder charge. This eliminates any human error or weather situations also.

Scott Satterlee has a very interesting method he’s developed that I’ve done some playing around with. The results I’ve gotten with his method (so far, with limited testing) have correlated exactly with what I’ve found using a Ladder or OCW.

10 Round Load Development Ladder Test


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[bpotter]

I suspect that is because they are all finding the same thing...a load area where adding powder does not change velocity greatly and bullet is highly stabilized for a given barrel. For example 160 gr 7 mm bullet at 2850 to 2950 will be constant
but the number of grains and range in charge weights will vary by powder. Some powders will be more accurate but the reason for that is more than raw velocity.

You might find a faster node that is
accurate and without excess pressure but it would probably take a slower burning powder.

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