ladder test results question regarding point of impact

[btm_54]

Is it possible when shooting a ladder test to have the holes you shoot in the target to be lower, as the amount of powder in each round increases? I was wondering whether there was anybody who have had the aforementioned experience. I always thought the more powder the higher the point of impact because the MV was higher.

 

[RonAKA]

Yes, they can go lower. The real question is whether or not the lower one is due to the muzzle direction at time of bullet exit, or just random inaccuracy. Here are ladder test graphs for three different bullets at 300 yards. Each point represents the average of three shots. All three flattened out at 3420 fps or so, but two dipped some. Not sure if POI really dipped or it was just random inaccuracy.

 

[260Ravage]

In ladder testing, I have witnessed the same scenario. I have always assumed it was the variation in the barrel whip. I try to develop my loads on the top side of the whip. I do not know if my assumptions are correct but it works for me.

 

[deadlyswift]

I have seen what your talking about in my own ladder test. I usally look for the top end node because I am looking for a load to shoot at 600 to 1000yrds. In one ladder test I seen the med node's POI lower than the low end node, Go figure?? So far I have done 6 ladder test and the top node is always at a higher POI. I'm guessing that the bullet is exiting the barrel at the top of the whip?

Ron,
I do like your graph! What software are you using to make the graph? Looks like it would really be something great to keep in my records. Usally I hand write and explain all my findings in note pads. Is this program user friendly? I really have got to catch up on my PC skills!
Mark

 

[RonAKA]

Ron,
I do like your graph! What software are you using to make the graph? Looks like it would really be something great to keep in my records. Usally I hand write and explain all my findings in note pads. Is this program user friendly? I really have got to catch up on my PC skills!
Mark

It is Microsoft's spreadsheet program Excel. More recently I have been using Open Office Calc, which is nearly identical to Excel, but is available to download for free from Oracle. Spreadsheets work well for storing data, and manipulating it -- calculating standard deviation, extreme spread, averages, etc, and obviously graphing. They can be a little daunting to use, but the basics are fairly simple. I've attached a copy of spreadsheet I used to make the graph above. I suspect you will need either Excel or Open Office Calc to open it though.

 

[Gregg Jacob]

RonAKA was nice enough to send me his Excel file, from another post, so I could work this up to keep my ladder test documented. Thanks again Ron.

 

[JohnMill]

Gregg (and all) please reread Jason's article on the ladder test.
No one on these 2 threads got it.
Charting a ladder test may serve a purpose but in a properly done ladder test, the target is all the chart you need.
Honest, I am just trying to help.
John

 

[Gregg Jacob]

Gregg (and all) please reread Jason's article on the ladder test.
No one on these 2 threads got it.
Charting a ladder test may serve a purpose but in a properly done ladder test, the target is all the chart you need.
Honest, I am just trying to help.
John

Guess I'm getting too old, 62, but I loose targets, and in a year or more I might like to review it, sell the gun with info, or have someone ask me about a load, and need something to reference it to. You can see I put the pic of the target with the data because I agreee with you the target is all you need...but everybit helps.

 

[RonAKA]

Gregg (and all) please reread Jason's article on the ladder test.
No one on these 2 threads got it.
Charting a ladder test may serve a purpose but in a properly done ladder test, the target is all the chart you need.
Honest, I am just trying to help.
John

John, I'm not sure what article you are talking about. Is there a link to it?

I know the original ladder test used one cartridge per load, and you look for a scrunched part of the "ladder". In theory it works. However, there are some practical issues. The first one for me is that at 300 meters my 6-24x42 Sightron Big Sky just barely lets me see holes in the target as long as they are in the white. I don't have a spotting scope, so I had to come up with a different way. The second issue is that unless you have a 1/8 MOA gun it is highly risky to assume one bullet hole represents the load. Just normal variance can create the appearance of a scrunched spot, where there really isn't one. My preference is to use three holes per load and average them.

So when you put those two issues together, you can solve them by using a separate target for each load. No need to see the holes until you go down to retrieve them all. After you find the average of each, then you just plot the graph and look for flat spots. It really is all the same thing, just different ways of getting there.

 

[JohnMill]

Ron, here's the link. I didn't know there was another place that described a ladder test so that everyone had read this one. Sorry. Hope this helps.
Hadn't thought much about it 'til you brought it up but i'm almost 69 and I'm chasing this acuracy thing just as hard now as I was when I got into it in '88 and it's not getting any easier. I learn from just about everyone. I've been to Williamsports BR school twice and just signed up for a third time. I raced motorcycles for 16 years now I'm racing bullets. Same game except the mistakes don't hurt as bad.
I do hope this helps. Jason is an excellent teacher as are all the others at Williamsport.
http://www.accurateshooter.com/technical-articles/long-range-load-development/

 

[RonAKA]

OK, thanks for the link. I've saved it. Here are a couple of other variations of it at the links below. I agree with the use of three shots per load. I think whether you do them as a ladder or on separate targets is just a matter of preference. You end up at the same spot, just a different road to get there.

http://www.desertsharpshooters.com/manuals/incredload.pdf

http://www.optimalchargeweight.embarqspace.com/#/ocw-instructions/4529817134