Ladder Test Question

[Wildboarem]

My first question has to do with vertical dispersion. Every ladder test I've done (@300yds.)has given me some results I don't know understand. Within the string, lets say from 42gr-45gr +/-.3 will have some bullets actually drop in elevation within the ten shots. 1-3- slowly climb, 4- is down around 2, 5-7- show a node but printing higher than 1-4, 8- is back down around 3, and 9 and 10 printing back up above 5-7. I hope this is clear as mud. What I'm saying is not all the bullets print vertical always gaining in elevation, some actually drop back down the ladder even though velocity is consistently climbing. Is this normal?

Next question is during ladder test or OCW does anyone find a particular node relevant to velocity. My .260 using 3 different powders (RL-17, IMR4350, H4350) and two different 140 gr. bullets (Amax, Barnes Burner). On the 300 yd ladder there is a definite node at around 2875fps, doesn't matter which powder or bullet. I went back through some older ladder test and it is consistent. Has anyone else experienced this? Or is it coincidence?

[fullersson]

Yes to your first question. I've seen that happen a good bit. I don't use a chronograph very much so I can't help you much there. Brian Brown.

[jimbo88mm]

Wildboarem,

I have been experimenting with a ladder test on one of my rifles. I have fired several strings. In a couple example, I could see a very clear rise in vertical elevation but I do occasionally see what I consider anomalies (where a higher charge shoots low). In my case I believe there are some varibles that can contribute:

1) I pulled the shot.
2) maybe my load was off.

I don't know what you are using to measure powder but when incrementing the charge .2 or .3 grains, you're scale and reloading technique need to be spot on.

On your second question.. yes, I do believe there is a correlation between velocity and the nodes. I always looked at reading the elevation of the holes on the target as a way of measuring the velocity without even using a chronograph.

[GaCop]

Pay close attention to the pressure required to seat your bullets. A bullet that seats easier in the case neck may cause that round to clock a lower velocity and print lower even though it's loaded with a higher charge weight. Even for ladder testing, I like firing over a chronograph to see each velocity for that string. HTH

[kelbro]

It has to do with barrel harmonics.

http://www.varmintal.com/amode.htm

[Dennis]

A bullet that seats easier in the case neck may cause that round to clock a lower velocity and print lower even though it's loaded with a higher charge weight.

I would have thought the exact opposite! I have my neck tension set at .002. I guess I have the right powder/bullet combo for things to work out!

[Wildboarem]

Kelbro, thanks for the link. It took a while to wrap my head around it all, but fascinating and informative.

[justinp61]

Not to hi-jack, but is a ladder test useful at only 100 yards?

[earl39]

Not to hi-jack, but is a ladder test useful at only 100 yards?

Yes and no. The more distance the more it will show node groups. At 100 yards there is a good chance you could stack a lot of different loads into such a small group you couldn't tell what loads are really in the node so more distance the better. That being said sometimes loads will show up at 100 yards that stand out and should be tested at longer distance.

[unclokie]

Not to hi-jack, but is a ladder test useful at only 100 yards?

Yes and no. The more distance the more it will show node groups. At 100 yards there is a good chance you could stack a lot of different loads into such a small group you couldn't tell what loads are really in the node so more distance the better. That being said sometimes loads will show up at 100 yards that stand out and should be tested at longer distance.

I am new to the site and to the concept of "ladder" testing. Is there a proceedure available that describes the steps you use to perform a ladder test that is available on the site or another? I am not a newbe exactly but I would like to know as much about this as possible.
Thanks, :-\ Otis

[Wildboarem]

Heres one resource [http://kingfisher.0catch.com/guns/laddertest.explanation.html].

Essentially you load incrementally ( lets say 42gr- 45 gr of chosen powder in 1% increments. 42.0,42.3, 42.6, 42.9, 43.2 and so on.) and shoot 1 round of each load at the same point of aim. The point of impact should climb, like a ladder. Where the POI starts to string horizontally rather than vertically is what your looking for ( accuracy node) you will later develop your load within that range. One tip I found that works really well is using colored sharpies to color the bullets. When shooting the ladder at 300 yds+ can sometimes be tough to know exactly which bullet is which. On white paper the colors show up pretty good, even ones that are two-tone ( half blue, half red etc.)