A good node for a load should be insensitive enough for a minor - up to a .3gr at least deviation in powder drop amount. It will be perfectly visible in a 10 rd group.Surely, because a single 3 shot group is a respectable statistical representation.
Have you ever tried to reproduce an OCW test? What about try shooting it with more than 3 shot groups, 30-shot groups would surely up the statistical proof. Seems like every time ive seen it tried it comes up unrepeatable.
Take Lou Murdica for example. If you have never heard of him id suggest doing a little research as he is pretty well versed in ballistics. Lou has some of the most state of the art equipment and has done alot of testing for bullet manufacturers. He tests with rail guns in a tunnel which leads him to eliminate almost all outside influences. Ill attach a few of his findings here.
"Well, here's what I got today. I've got some more work I'd like to do and I'll see if I can get the Excel sheet uploaded here-- if nothing else I'll try to get it in a google doc or something.
Each dot represents a 5 round group MPOI (Scale is inches at 200yd). Each color represents a charge weight. I will be further breaking these into subsets of 1st, 2nd, 3rd, 4th, 5th, and 6th group of each charge weight. I'm about half way through that and I'll spoil it for you-- they don't repeat. These are less messy to look at, too.
This data set has the most resolution, but the gun was moved between some of the sets, so each set of 35 is referenced off of its own MPOI. Some 'global' position could be lost, but in my experience with other powder ladders, even over 3-4gr spreads the MPOI of the large data sets is within about a .08 MOA window in the worst cases.
Nevertheless, if you look at this below, you'll see 5 shot group MPOI of the same ammo varies in a .35ish MOA window... so even if my 'global' 35 shot group is .04 or .06 or .08 MOA in error, it's completely swallowed up by the randomness of 5 shot samples-- which has been my point all along. There are not many viable conclusions to draw from 5-shot groups, and the difference in dispersion performance or MPOI between two varied powder charges is not among them. These patterns repeat over and over. Noisy data until 15-30 rounds in... It's the same thing you learn in probability and statistics, it's the same rule of thumbs that every statistical process control/analysis people use... Somehow people think shooting is different I guess?
Sorry if I'm short, but I've had this play out already. I started with shoulder fired rifles & contoured barrels with me aiming them and had people claim I wasn't steady enough to have valid data. I switched to an accuracy fixture and 1.25" barrels and get told that it's too rigid to show OCW results. My data came to the same conclusion both ways... I've burned out barrels doing this and have people tell me I'm wrong with no supporting data, or refute large sample data with more small sample data. It gets old."
I’d also be interested in seeing more proof that SD and ES mean nothing. Im not the most versed on physics or ballistics but im pretty confident that a projectile with a large velocity spread will not be consistent at 1000 yards. IMO these numbers are some of the best representations of consistency. If you want accuracy you need consistency and the most effective and most reliable test is velocity testing. It eliminates a lot of variables that are present in POI testing.
BTW I'm not trying to say that harmonics are non-existent all im saying is that looking for POI shifts at 100 yards with an OCW test doesn't seam to be the best way and has been found to be unrepeatable.
I played enough with that for now and a way going with 5 rd groups initially to find best spots and a subsequent 10rd batch loaded groups was the fastest way to proceed.