Re: Quick question on OCW testing
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: OldTex</div><div class="ubbcode-body">It's important to remember the whole point of OCW or the Audette ladder - It's not about finding the smallest group, it's about finding the load where your POI will be least sensitive to variations in velocity (usually caused by changes in ambient conditions). OCW is based on Audette's work, and Audette was a military man looking for ammo that would hit its target no matter what conditions the soldiers found themselves in.
So yes, you're looking for consecutive groups. These are the groups where the POI stayed pretty much the same even though velocities were changing.
OCW is nothing more than an Audette ladder with three shots fired at each powder level. It seeks to avoid the influence of barrel heat, barrel fouling, shooter's subconscious influence or fatigue, etc. by changing the shooting order. Using the different points of aim makes it easier to keep track of which hole is which on the target but it can add another set of errors into the equation because the shooter has to shift his gun and body between every shot. And it adds the need for a convoluted measuring system.
HERE is an alternative way of doing the same thing as OCW. The shooter keeps track of which hole is which by using colored projectiles. But instead of the tedious measuring system, the nodes are obvious to the naked eye. It still uses the round-robin firing sequence like OCW but you aren't shifting your gun around 20 times during the test. (just like the other methods, you can use whatever distance you want)
It's a personal choice which method you use. They are all looking for the same result. </div></div>
I believe if you sat down over lunch with Dan Newberry he would gladly tell you that OCW is certainly NOT based on Audette......if you doubt me then by all means follow the link above and ask him yourself.
OCW's main concern is addressing barrel harmonics, by actually SEEING the low side scatter nodes close up, the accuracy node spread across a range of pressures, and the upper side scatter node begin to open. You don't see that, that precisely, with a normally done ladder test.
Audette is an external function of velocity and BC over distance, and sees very little regarding barrel harmonics due to the broader increases in pressure. OCW is a function of barrel time, defined by very small increases in charge weight, and then seating depth. The method is not just another variation of Audette because the data obtained is much more refined and exact, and is mainly watching the physics of the shooting platform itself.
The inherent tolerance to conditional variance defaulted to the physics of a properly done OCW is just icing on the cake......