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Posted: 5/24/2012 12:34:50 PM EDT
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I'm not too quick lately so I could use some help on explaining how ladder tests should be conducted and what they tell me. From what I read I want to load up 10 rounds each starting at the lowest charge and going to the highest charge according to my load book, with the steps in between those two. Then go shoot them and see what groups best. Is this the gist of it or am I missing something? |
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Google "how a ladder test works". First link: http://www.6mmbr.com/laddertest.html
The number one thing I see most people missing is that this must be done at a pretty appreciable range - you will get far more out of this test at 300+ yards than you will at anything shorter than that with most high power rifles. The idea is to find a load that gives you the most consistent performance per change in powder charge - in other words, you're going to shoot the 'ladder', and look for points where the bullets land closely together. |
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Quoted: Google "how a ladder test works". First link: http://www.6mmbr.com/laddertest.html The number one thing I see most people missing is that this must be done at a pretty appreciable range - you will get far more out of this test at 300+ yards than you will at anything shorter than that with most high power rifles. The idea is to find a load that gives you the most consistent performance per change in powder charge - in other words, you're going to shoot the 'ladder', and look for points where the bullets land closely together. That is what i read and left me with these questions. |
| since you don't have access to a 300+ yard range, do the OCW instead. I have done this at 100 and it works well |
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Quoted:
That was the other problem I have, no range over 100 yards readily available. Is it worth doing at 100 yards? No, a ladder test really isn't worth doing at 100. The OCW test mentioned above is good, but do it with 5 shots instead of 3, if you can take the time to do it. |
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I ladder test my rounds at 50yds. The groups are close, but I can see a difference. I can REALLY see the difference when I scan the group into my computer and use "On Target" to analyze the groups. It can tell you max height, width, average, and distance to aiming point.
My first group for the ladder is in 0.5gr increments from low to high. As I get to the high end, I pay attention to how the gun reacts when the bullet is fired and look for signs of overpressure on the case. Once I find what group is best, I do another ladder in 0.2 gr increments. So if the best of the first ladder is around 24.0gr, the next ladder will be 23.6, 23.8, 24.0, 24.2, and 24.4. Usually one of those will be the best. I should also point out that I shoot with iron sights. Below is an example of what you can expect. Notice that 24.0 was the best of the 0.5gr increments, and 24.2 was the best of the second group: 23.0gr 
23.5gr 
24.0gr 
24.2gr 
24.5gr 
25.0gr 
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Quoted: since you don't have access to a 300+ yard range, do the OCW instead. I have done this at 100 and it works well  Here's a link to one particular idiot's (archived) OCW thread. In spite of me obviously doing it wrong, it WAS useful. |
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Quoted:
I ladder test my rounds at 50yds. The groups are close, but I can see a difference. I can REALLY see the difference when I scan the group into my computer and use "On Target" to analyze the groups. It can tell you max height, width, average, and distance to aiming point. My first group for the ladder is in 0.5gr increments from low to high. As I get to the high end, I pay attention to how the gun reacts when the bullet is fired and look for signs of overpressure on the case. Once I find what group is best, I do another ladder in 0.2 gr increments. So if the best of the first ladder is around 24.0gr, the next ladder will be 23.6, 23.8, 24.0, 24.2, and 24.4. Usually one of those will be the best. I should also point out that I shoot with iron sights. Below is an example of what you can expect. Notice that 24.0 was the best of the 0.5gr increments, and 24.2 was the best of the second group: 23.0gr http://i1119.photobucket.com/albums/k637/ajroyer/23-0gr8208XBR.jpg 23.5gr http://i1119.photobucket.com/albums/k637/ajroyer/23-5gr8208XBR.jpg 24.0gr http://i1119.photobucket.com/albums/k637/ajroyer/24-0gr8208XBR.jpg 24.2gr http://i1119.photobucket.com/albums/k637/ajroyer/24-2gr8208XBR.jpg 24.5gr http://i1119.photobucket.com/albums/k637/ajroyer/24-5gr8208XBR.jpg 25.0gr http://i1119.photobucket.com/albums/k637/ajroyer/25-0gr8208XBR.jpg What you did is closer to the OCW process than what's usually referred to as a 'ladder test'. Usually you fire one shot of each load density, and they will 'climb' the paper, but there will usually be a couple of shots that don't vary much - this is generally treated as an 'accuracy node', where the accuracy of the round won't be very sensitive to variations in powder charge. Unfortunately, this is a really limited approach to developing an accurate load, so while you may luck out with having the right combination of other factors in your load to produce an accurate round, you very well may not, since you're only looking at powder charge. The key is to do as you have done, and look at the actual grouping capacity of a given load, and to vary the other factors involved as well. This is where a more developed statistical analysis of the variables involved becomes useful. Then again, I'm the OCD type 
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Quoted: Quoted: since you don't have access to a 300+ yard range, do the OCW instead. I have done this at 100 and it works well Here's a link to one particular idiot's (archived) OCW thread. In spite of me obviously doing it wrong, it WAS useful. I see what you did there.  |
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