Wow it's been a while since I updated this.
I had an awesome practice today and I'm feeling exhilarated about the rest of the season. The drill today was the accelerator. I started off kind of crappy, even getting D hits on the close target. This had been happening a lot this year, getting bad hits without calling them, then walking up to the target and saying "WTF how did that happen?" Typically the gun feels kind of floppy in recoil, as the front sight goes up then dips way down into the D zone, and seems to oscillate a few times before settling in. It would feel like the 2nd shot broke as the gun was still flopping around. Not good.
So I got kind of pissed today and went back to the fundamentals. I decided to consciously grip the gun as hard as possible with my support hand, then did a 5.3 second run with 2 C's. With just this one change I started hitting A's and close C's and started to enjoy shooting again.
It's weird because I honestly do grip hard in dry fire practice, and I'm pretty sure of this because my left hand and forearm get sore. But in live fire I must have been slacking, so when the gun recoiled in my weak grip I was flipping my hands back down and over-driving the gun. The whole thing makes sense to me now because I can always get a good group of A hits on a 7 yard Bill drill. It's probably because when firing 6 shots on one target, you know intuitively that you really have to drive the gun with a tight grip.
So, gripping hard and locking the support hand wrist results in more As when shooting fast. I probably should have figured this out sooner and not blamed trigger control alone. But I feel like I made a breakthrough in my shooting today.