That's a very good, well written article. AND it's correct! I only wish he would have told us which bullet he was using,(mold #),, and what the alloy, lube, and what it was sized at. I don't have a triple deuce, but some day I WILL have a bolt action in .223. I already have several .223 molds, and have tried casting some bullets.
I have a 16" contender barrel, that I tried some in, with mixed results. I also tried a few in my AR, even though the common knowledge is that should not work! The main problem is with the gas system getting clogged, the few I shot did NOT do that, but they also did not cycle the action. Accuracy was only so-so.
I'm gonna retire in 01-2012, so I will have the time to experiment.
My experience with cast in 45/70 tells me he's right on the numbers. Softer alloys begin to deteriorate when you push over a certain velocity/pressure. As he, and Richard Lee says, it's the pressure related to the alloy, that's the important factor. The velocity is what it is. Or in other words, you can manipulate the velocity by controlling the hardness of your alloy and the powder choice to control the pressure.