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I guess I've been fortunate in the past, and found load recipes that have been quite accurate for my shooting needs. I would like to try conducting a ladder test for my 2 ar's in .223. What would be a good incremental increase of powder to conduct a good test? Currently I'm working with 55 gr pills and Winchester 748. Would .5 gr increments be too much or could that set the baseline? Then I could do some fine tuning from there. The range is 22.5 gr to 25 gr.
In 223 I usually worked in .2 grn increments looking for the clusters of shots then tested at the mid point of the clusters. I was lucky in that we loaded at the range My wife loading each round as I shot it. We then tested the mid points and after that in each of the 3 ARs.
In my bolt gun I loaded the spread of min / max loads in .3 grain incriments X 5 ea., shot individual bulls @ 100yds., picked the tightest/2'nd fastest/group and went up and down from there with .1 grain increments. I picked the 2'nd fastest group because my fastest/tightest group was borderline showing primer pressure/flatness.
I did a round robin ladder test, tested my loads alternating each shot on the same target. .3gr is what I was turned onto using this past summer and I liked how quickly I could identify loads which had potential and could tune more later on.
I used colored sharpies to paint the bullet nose (Full red, Half red, blue and blue red and naked ) work best on the heavy cardboard targets I was shooting. That allows me to shoot 5 different loads alternating to take any set up bias out of the equation as much as possible. I can even load my magazine full up (25 round Pmag in the RPR) and give the barrel time to cool or not between shots.
I usually loaded in .2 grain increments with 3 rounds each, then picked the tightest group. But this method has me interested:
http://www.65guys.com/10-round-load-...t-ladder-test/
The original Audette ladder of working up loads was 1 round at each step fired at the same target same aiming point and tracking each shot. he idea of this load work up was to find the "dead spot" in the harmonics node for the load. Looking for where 2-3 or 4 shots clustered with the different steps in charge. IE if 23.2 23.4 and 23.6 of xxx powder cluster together when shot then it was tested again at 23.4 grns of xxx for accuracy. The thinking was to find a load that would allow .5-.6 grn variation and still go into the group. I also fund that loads worked up in this manner tend to work well in many different rifles.
Do you have a copy of Creighton's original article which appeared in Precision Shooting?Quote:
Originally Posted by country gent
And if so could you possibly can it and post a .pdf? I'm sure folks would like that.
No I don't have it anymore. Wish I did. I don't believe the article in Preccison Shooting was the original on it though, I think it was a reiteration from an earlier article he done.
Look up 'optimal charge weight' as a method.....basically what country gent and Outpost are speaking to above. I use it.....and I have found it to be very reliable, particularly for finding a hunting load that works well in all conditions. You might not wring every ounce of accuracy out of a rifle this way....but you will find a load that shoots well always.
I just did a quick search for the original article on the Audette ladder method. I found a lot of information and one refrence to where he outlined it during a High Power clinic around 1980. Creighton Auddette was a long range shooter Palma shooter and had one the nationals across the coarse. He was also an engineer at Frankfurt Arsenal. I think his load work up predates the 80s clinic also. Just cant find it.
chutestrate
I'm not exactly sure how Audette's "Ladder Test" got turned into a shortcut method of working up a load. Some think it works but I've tried it with numerous rifles of various cartridges with know accuracy loads and the "ladder" failed in every instance to indicate that accuracy load. Given the variances of random bullet dispersion in a group and ES variances attempting to use one shot of any load and expecting reliable feedback has never proven out. At least not to find the best accuracy load.
As country gent points out Audette's ladder test was an attempt to find a +/- load variance produce by his electronic powder thrower with IMR4350 that would "group" at long range (600 to 1000 yards). It was never intended to be used in working up a load to begin with. How it got changed into that is a mystery.
With .223s I use a .3 gr increment and use initial 3 shot increments chronographing them. Once in the expected/intended velocity range I then switch to 10 shot test strings (usually no more than 5 incremental tests). If one proves more accurate and has an ES/SD in nominal range I then load 3 ten shot strings of that. If all shoots well I then know with those components what really is the "accuracy" load in that rifle.
BTW; 25 gr 748 under a 55 gr bullet (jacketed) is pretty much a common "starting" load. Maximum loads listed in many manuals is 28 gr. Starting at 22.5 gr and working up to 25 gr is going to give very sub par ballistics.
I'd be loading in 0.2 increments for a case that small. Usually do 0.3 for .308 and .30-06 family cases. Wouldn't go as much as 0.5 until I was dealing with something large.