Ladder test

[Bart B.]

My only concern about ladder tests is how statically significant one shot's vertical place on the ladder represents the center of a 10 or 20 shot group with that load.

How does one determine that the upper shot hole of two close ones is not the highest one a 10 shot group the charge would produce? Or the lowest one as the odds are the same?

 

[steve123]

My only concern about ladder tests is how statically significant one shot's vertical place on the ladder represents the center of a 10 or 20 shot group with that load.

How does one determine that the upper shot hole of two close ones is not the highest one a 10 shot group the charge would produce? Or the lowest one as the odds are the same?

By repeating the ladder test.

Go look at Tom's and Alex's 1000Y ladders, but they took it a step further by shooting 3 shots in the suspected node, derived from the first test/tests. Nothing wrong with confirmation or additional work to prove preliminary results.

Heck, even those crappy 4" groups at 1000Y that are slightly out of tune most of us would jump up and down for, lol.

 

[CharlieNC]

My only concern about ladder tests is how statically significant one shot's vertical place on the ladder represents the center of a 10 or 20 shot group with that load.

How does one determine that the upper shot hole of two close ones is not the highest one a 10 shot group the charge would produce? Or the lowest one as the odds are the same?

Shoot smaller increments between charge weights and/or duplicate loads for each. The focus is not on the exact location of any single shot but to fit a smooth curve to the poi vs charge, which can be done mathmatically or even visually. With this approach the often stated "need 20 shots to statistically define that point" is a mis-applied concept. I typically shoot 2 per charge, and yes correlate the group size from those to the node as well.

This is perhaps more easily portrayed using velocity as the response. Measuring a single velocity across a charge weight ladder, a smooth curve response from say 8 charges can be used to calculate the velocity at the node. This will generally yield a better answer than measuring the magical 20 shots at that single given charge.

The only thing statistically magical about 20 shots is that beyond that number you have reached the point of diminishing returns. 20 does not mean the answer will have a particular significance. Likewise it is frequently possible to demonstrate items are statistically with much less than 20. Its all about signal : noise ratio.

 

[Clark]

My only concern about ladder tests is how statically significant one shot's vertical place on the ladder represents the center of a 10 or 20 shot group with that load.

How does one determine that the upper shot hole of two close ones is not the highest one a 10 shot group the charge would produce? Or the lowest one as the odds are the same?

Bart, I have followed you for 21 years on usenet and now www.
You represent the highest level or precision and I represent the lowest.
Any accuracy ritual you can eliminate, I can copy... But there must be many you find useful that would be down in the noise for me.
I am merely shooting deer at 650 yards, the ladder test may well be down there with deburring flash holes from my perspective.

 

[Kurt Blasser]

You shoot in increasing increments and see where you have similar points of impacts. This is the first result when I google "Ladder test" and it should say pretty much all there is to say about the matter http://www.6mmbr.com/laddertest.html

And with zero words

Is there a distance that would be considered a minimum, to see the POI open up?

 

[Mulligan]

http://forum.accurateshooter.com/threads/ladder-testing.3894169/

CW

 

[spife7980]

Is there a distance that would be considered a minimum, to see the POI open up?

300, much better at 5-600 or out as far as you can shoot

 

[BountyHunter]

IMO do not just look at POI, record each shots MV and you will see that the MVs on a node tend to be very close and then jump. For example my 300 WSM would jump around 25 fps at .3 gr intervals not in a node and then for 2-3 shots it would drop to around 6-8 for each shot in that node. Then it would start jumping around 25 again until the higher node. Compare the MV nodes to the POI nodes before you decide.