Having fun with load dev. Tod is going to like this one.
Reloaded another batch of .223 to test the next calm day I can get to the range. Way back, I used a 3-round OCW ladder type test to look for the sine wave pattern talked about.
23.6 and 25.0 fit that.
Tried halfway between as well, due to that 3% rule.
Those should have been solid.
Tried an anti-node of 24.7. That was supposed to suck.
Reality: 23.6 was good the first 5-round group, then the velocities started to climb for future groups, and the groups got worse.
The four 25.0 groups were all under 1/2 moa. Velocities climbed for that load over the morning, but the groups remained stable.
The (hopeful) 24.3 group sucked donkey balls.
The supposed anti-node was the 2nd best load overall. Sound familiar, Tod?
Now Tod is grinning or laughing.

New batch just made will test 23.6 and 25.0 again, and I didn’t clean the barrel this time. So I’ll see if this barrel speeds up as it warms up, or if it behaves this way after a cleaning.
Plus testing more lower charges just below 23.6 to find a lower velocity accuracy load, especially if this barrel like to speed up as you shoot it.