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ladder test? does it work

 
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  #15  
Old 03-20-2007, 03:31 PM
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Re: ladder test? does it work

[ QUOTE ]
Funny you should mention that, as I have a degree in Applied Mathematics and Computer Science. A Ladder test is not a single data point. It is a series of experiments that give data points across the range of its independent variable (powder charge).

[/ QUOTE ]

I think computer science must be very different than classical physics, chemistry, and the other "sciences".

Each "load" is a data point. The string of data points is the test.

For the information to be valid, each load must be repeatable. If it's not, then a large enough sample of THAT load must be taken so that the average represents a value that is repeatable... otherwise each time the "experiment" is repeated, you get a different result, and that is not acceptable in any field of science.

If you like ladder tests, do them.


He asked for opinions. You have your opinion and experience, and I have mine. Mine does not match yours.

He can choose from what he reads.

.
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  #16  
Old 03-20-2007, 04:14 PM
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Re: ladder test? does it work

I believe the ladder test will get you pointed in the right direction but it is not going to find the perfect load every time. Like CS said, too many holes and variables IT WILL NOT ACCOUNT FOR. One of which is the fact that it works better at greater distances and that also happens to be it's ultimate achilles heel. Very few of us can ever find a day where it is calm enough to be able to eliminate the possible data interference inserted by the weather. And descering x (being the weather) and y (being the ladder) even in calm conditions is hard if there is any mirage.

In my humble opinion, ladders were invented for guys who either didn't want to buy chronographs or didn't know how to read what they were telling them. A few guys have since added the chrono to the equation, but then if you're doing that, you might as well just use the chrono and throw out the ladder.
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  #17  
Old 03-20-2007, 04:35 PM
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Re: ladder test? does it work

[ QUOTE ]
[ QUOTE ]
Funny you should mention that, as I have a degree in Applied Mathematics and Computer Science. A Ladder test is not a single data point. It is a series of experiments that give data points across the range of its independent variable (powder charge).

[/ QUOTE ]

I think computer science must be very different than classical physics, chemistry, and the other "sciences".



[/ QUOTE ]

Actually its a degree in Applied Mathematics. All my electives where Computer Science, so I could have had either BS. But thats really irrelevant isn't it?

[ QUOTE ]


Each "load" is a data point. The string of data points is the test.

For the information to be valid, each load must be repeatable. If it's not, then a large enough sample of THAT load must be taken so that the average represents a value that is repeatable... otherwise each time the "experiment" is repeated, you get a different result, and that is not acceptable in any field of science.



[/ QUOTE ]

In physical sciences with real life experiments, you can NEVER expect data values to match 100% exactly the same every time. But what you can expect is that a set of data points will 'tend' to represent the entire population. EVEN FOR VERY SMALL SAMPLES.

Of the last 13 groups (shot with 'good' loads) I've shot and recorded for my 7rm, I have an average of .4125 MOA. The standard deviation is around .062 MOA, giving me a 95% probability that any good load from my rifle will shoot within .124 MOA (2 stdev's from the mean) of its average group.

With the ladder test method, I am not just looking for a good shooting load. I'm looking for a load that is tolerant of varying load densities (+- .3gr powder). I want loads like this because they tend (IN MY RIFLES) to be more consistent over varying field conditions.

So, during a a ladder test, each shot is likely (95% probability) to fall within 2 standard deviations of the average for that load. For any 3 shots within a ladder test, it is likely (86%) that they have ALL fallen within 2 stdev of their average. So, for a typical 20 shot ladder test, its likely that a couple of shots have fallen outside the 2 standard deviations, but unlikely that any/many have fallen outside 3 standard deviations of the average.

Put in other words, In MY RIFLE, the good groups will measure within 3 standard deviations (.19 MOA) of what they should (99% of the time).

That is Math. That is statistics. That is real world.

When I look at a ladder test for MY RIFLES, I can tell where the nodes are, based on historic evidence of behavior of MY RIFLES and my loading procedures.

Don
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  #18  
Old 03-20-2007, 04:43 PM
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Re: ladder test? does it work

[ QUOTE ]
I am going to give the ladder test a test. Once the weather around this WC Minnesota lakes country settles down
and warms up a tad. The wind has been blowing for three days. Range time soon however. Have a couple guns I need to develop loads for. This will be different than the way I am used to as well. Will post my results later.
1kstr

[/ QUOTE ]

FWIW,

When I am working up a load in windy conditions, I just ignore the horizontal aspect of the target. I measure each shot and its vertical distance from Point of Aim. This eliminates most of the wind effects from the equation and simplifies the analysis of the target.

I've found that ignoring the horizontal spread lets me concentrate more on making a good shot than trying to worry about the wind. I always verify the loads in good conditions later anyway.

Don
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  #19  
Old 03-20-2007, 06:03 PM
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Re: ladder test? does it work

I don't want to seem like I'm really into this argument because I realize what I say isn't going to stop people who use the ladder from doing it but there is a factor here that I will point out that might influence your outcome if you choose to use the ladder. And that point is this:

[ QUOTE ]
When I am working up a load in windy conditions, I just ignore the horizontal aspect of the target. I measure each shot and its vertical distance from Point of Aim. This eliminates most of the wind effects from the equation and simplifies the analysis of the target.


[/ QUOTE ]

Remember, wind does not just blow left and right. It also blows toward, against, diagnally, up, down, and all around. And a true left and/or right wind will also cause slight vertical in bullet impacts as well. So to say that you can descern all of this from what the load is actually doing may be a big accomplishment. Then throw in a little mirage and things get even stickier.

Now, if you could just find an indoor 1000 yard range.....
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  #20  
Old 03-20-2007, 06:27 PM
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Join Date: Oct 2005
Location: Michigan
Posts: 2,232
Re: ladder test? does it work

[ QUOTE ]
I don't want to seem like I'm really into this argument because I realize what I say isn't going to stop people who use the ladder from doing it but there is a factor here that I will point out that might influence your outcome if you choose to use the ladder. And that point is this:

[ QUOTE ]
When I am working up a load in windy conditions, I just ignore the horizontal aspect of the target. I measure each shot and its vertical distance from Point of Aim. This eliminates most of the wind effects from the equation and simplifies the analysis of the target.


[/ QUOTE ]

Remember, wind does not just blow left and right. It also blows toward, against, diagnally, up, down, and all around. And a true left and/or right wind will also cause slight vertical in bullet impacts as well. So to say that you can descern all of this from what the load is actually doing may be a big accomplishment. Then throw in a little mirage and things get even stickier.

Now, if you could just find an indoor 1000 yard range.....

[/ QUOTE ]

You are 100% correct, thats why I said "most". And by windy I meant 10mph wind changes at most. Where I shoot, the wind almost always blowing left to right, so the biggest component by far is horizontal. Certainly if someone is shooting across a canyon or somewhere that updrafts happen or with large shifts in direction to/from then you can't ignore the wind.

The biggest benefit for me with regard to ignoring the wind, is it allows me to concentrate on my hold and make it more consistent every time.

If its really windy, then I don't do any testing, just shooting.

GG, when you find that 1000yd indoor range, let me know [img]/ubbthreads/images/graemlins/grin.gif[/img] I'll buy the beer and pizza!
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  #21  
Old 03-20-2007, 06:35 PM
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Posts: 220
Re: ladder test? does it work

Wind gust to 40 mph. I don't mind a little wind but this is a bit much. Saturday sounds better.
1kstr.
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