BartB, you managed to hit on exactly what I'm thinking. I plan to fiddle with the two FL dies and try to set the shoulder back a bit less. I think the shoulder is getting set back too far with one or both of those dies. And I plan to ease the bushing die back off the case more than the 1/16 of a turn that Redding suggested. Regarding the Redding Type S FL bushing die, I can't accept that my accuracy was so poor with those reloads. It seems obvious to me that I'm not doing something right. More shooting to follow.
Hummer70, I'm loading the bullet just off the lands, though if I had to tell you at this moment how far off, I'd probably be lying to you. When I originally started shooting this load combination, I did vary COAL to see what shot best and settled on the length I used yesterday.
As I loaded and shot the various rounds, I noticed very interesting differences in several areas. The FL sized rounds, using the standard Redding die, showed higher pressure signs than the others did. I'll assume for now that it was due to being resized completely to a smaller interior volume. Also, the bullets required more effort to seat. The least seating effort was with the Lee Collet Dies, which required very little effort. That might, however, have been because the case necks were likely work hardened and didn't shrink around the mandrel as much as new brass might.
Also of minor interest is that different resizing dies caused minor differences in POI on the targets. I'll assume that's due to pressure variations caused by FL versus NK sizing and case volume differences.
So the question for me now is "what's the best die for loading my 223?" With rounds from the Lee Collet Die putting 9 of 15 rounds into one hole, I've just got to play with that die some more. If that many bullets went into the same hole, why did I have 6 flyers? Was it something I did? If I shoot a 5 round 'Lee Collet' group with a cold barrel for each round, will I get one big hole. We will see. If I decide to go with one of the FL dies, I've got to reduce shoulder setback. Brian's question/suggestion above about my needing to buy and test a shoulder bump die was a good question, but I probably won't go to that extreme just yet.
I should mention that I'm using that Nosler 40 gr BT for two reasons: It shoots pretty darn good and I have a lot of them. In that 1 in 9 twist, I actually get better accuracy from that 65 gr Sierra GK, but I'm saving them for pigs and coyotes.