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Been doing a bit of*reading on load development processes. Found a couple of articles that may be of interest to some of you.
The original "ladder test", lots of theoty and physics !
http://www.desertsharpshooters.com/m...incredload.pdf
Round robin ladder test, makes a lot of sense to me. Like the way he negates barrel temp.
Long-Range Load Development
Very interesting approach, makes it easier to interpret the results IMHO
Load Development: Ladder Test - TheFirearmsForum.Com
Thanks for posting that up.
I did the round-robin version yesterday after my daughter knocked my scales off the bench (smashed them pretty bad!!!) so I ended up getting a new set of scales and then I realised that my old scales although very repeatable, weren't 100% accurate...so my load data was only true to those scales grrrrrr!!!!!!!!!!!!!!!!!
Anyway, long story short I didn't have any loaded ammo that I could pull, no that would be too easy, so I had to start again! After a quick ladder test doing the round-robin shooting style had it punching .47'' groups again. It’s a No5 Trueflite barrel and is very fussy (short accuracy nodes) so you certainly know when you’re in a ‘’sweet spot’’ with this barrel. Unlike the The much heavier Sendero profiled barrel I got off Abe that will only shoot 0.5MOA no matter what you feed it...I guess it shows how a bit of meat in the barrel can hide a few sins when it comes to reloading eh?
My new attitude is to quit while ahead, so I'm happy to settle for 0.5MOA and not chase rainbows so to say. All that does is burn out barrels.
kj
I feel the argument Dan Newbery makes for preferring a OCW round robin over the Audette Ladder are convincing. The example you linked to with the 20 targets is textbook; how the author draws the conclusion that a node is indicated by targets 14-18 escapes me. All I'm seeing is statistical noise. The value of either method is dependent to a large extent on having the change in POI with powder charge variations dominant over spread due to the inherent accuracy of the rifle/load/shooter combination across the range of powder weights being tried. Without this it becomes difficult to pull anything meaningful out of the exercise and at the same time the value of trying to locate a node is then also questionable. A OCW round robin is better in this regard than a ladder.
Tx Puffin, interesting point, will do some more reading...
The part I like about the 20 target version is that it (potentially) gives you an easier way to interpret ladder results especially if you are doing relatively short range tests. With a lot of kit these days, 20 shot string at 100m - trying to figure out which shot is which is pretty hopeless.
If there are other processes specifically geared to doing load development when you are limited by the distance you can test at (either due to range or caliber i.e. 7.62x39), I'm keen to get more info.
on one of those links it goes on about colouring the projectiles with permanant marker to figure out which shot it which. it works well shooting cardboard.Quote:
Originally Posted by ebf
you just have to have a code writen down.
Puffin, mate just want to say thanks for pointing me at OCW
Most of my previous reloading was high volume pistol and straight-wall rifle cases, basically according to the manual.
Did some more reading: OCW Overview - Dan Newberry's OCW Load Development System
Soooo, just to make sure I have my head completely around this process. Suppose I want to check for the best load amongst 3 store-bought brands of ammo.
3 targets, 3 rounds each per of brand A, B and C
Brand A - Target 1
Brand B - Target 2
Brand C - Target 3
repeat 3 times, and vary the cooling periods etc.
at the end look for the closest POI rather than smallest group ?
ebf, with your factory load example the variable of interest is just the brand, A, B, or C. In this case I would shoot as many as I can afford to use, one target per type as you plan to do keeps the results separate. The more you shoot though the more statistically significant will be the differences in the observed size of each group. Letting the barrel cool between shots as time allows minimises a possible cause of POI change as you indicated.
For your example with factory ammo it is group size that is of interest. With OCW it is the movement in the average POI that is being looked at. “Round Robin” is just an averaging tool.
Taking these shots in a Round Robin ( A,B,C,A,B,C etc) is intended to average out some non-random changes in POIs that are not linked to the variation in the ammunition being investigated (be it brand, powder weight, seating depth etc. ) - these might be changes in your "set-up" at the bench between shots or groups of shots, progressive shooter fatigue, fouling of the barrel and so on.
The reverse side is that if using a Round Robin to test different factory loads there may (note: may) be interaction between the the different brands as you cycle round them since you would be mixing powder type and jacket material. This does not apply for OCW where bullet and powder are constants. So possible pros&cons either way. I might be inclined to pass up on the round robin altogether and instead start with a clean barrel for Brand-A, shoot 2-3 foulers and then your group, thoroughly clean the barrel for powder & copper and repeat for brand B, repeat again for brand C. Provided you don’t end up shooting one load “better” than the others it could be a way of giving each load a fair crack. Just a thought.
The Optimum Charge Weight method as the name indicates is really for developing hand loads where the powder charge is being varied (also good for seating depth with barrel time typically fixed) and where this exit time-to-barrel vibration relationship can be optimised to minimise the effect of reloading tolerances.
With a given factory load the shooter has no control over when the bullet leaves the barrel in relation to any stationary points or “nodes” in the flexing of the barrel so OCW cannot be applied. With different loads each type will likely exit with different barrel times having also excited vibrational differences in the barrel, and there will be a component of the overall group size resulting as a function of this with the consistency of the ammo (what OCW is looking at). The resulting average POI for groups with each type will probably also be different, but then you haven’t just changed one variable by changing ammo types. The group size will typically be dominated by the other factors that determine whether a rifle “likes” a particular load and of course shooting ability. I mention this only because in my case poor shooting skills limit the extent of any load development I can achieve so I have to be content with understanding the theory without being able to put it into practice.:oh noes:
Tx again Puffin,
Will be interesting to see difference, if any, with fouler + groups approach vs round robin for factory - might give that a go next week.
Hehe, agree fully with your comments about reloading ability exceeding shooting ability ;)
Rushy, has all this theory completely scared you off of reloading ? :P
No ebf, I have never had an interest in the subject nor seen the need to understand it as I am quite content with buying factory made as i tend to shoot only for meat and pragmatically, dead is dead so in the end for me it doesn't matter what type of projectile it was and what speed it was travelling as long as I hit the animal and cleanly killed it (which is what I tend to do).Quote:
Originally Posted by ebf
You will note that I stay out of the techo threads (except to poke the odd bit of shit from time to time) as I really don't know about the stuff you guys talk about and am quite happy not knowing or caring about it. Besides I look at some of the pictures posted of shot placement on targets and think to myself "but he / she never hit the aim point so why are they so excited". Trust me on this, you really don't want me taking an interest in them as there is nothing worse than a Rushy who thinks he knows shit.
Classic :thumbsup:Quote:
Originally Posted by Rushy
That was the bit I liked:yarr:
he he rushy ive noticed that......
you ve not commented yet ...in the photo toolbars and smiley thread :o
Show me how and I'd be happy to. Or are you taking the piss out of me GJ? About time someone did if you are.Quote:
Originally Posted by geezejonesy
me take the piss ................... never RUSHY never not about you :innocent: