Update.
Ray at Manson measured my reamers, brass, and took a look at the die.
The chamber reamer measures in spec. It's good to go. The expansion ring (largest diameter) is at 0.260 instead of 0.200. He said that because the reamer measures in spec , the only way for the brass to be that large at that point is an oversized chamber or really over pressure loads, which there doesn't seem to be evidence of the latter.
The resize reamer is slightly out of spec at the 0.200 line. It measures at 0.4984, where it should be under 0.498. they will be fixing this dimension on the reamer. Fitting the resize reamer into the sizing die, he said he could wiggle the reamer, meaning that the die is larger than the reamer dimensions. So the sizing die is also cut oversized.
so, having a new die made with the fixed resize reamer should alleviate some issues I'm having. However , I'd have to have the barrel set back in order to fix the chamber dimension issue.
There's no answer for my cases growing 0.003/load, other than it happens and is likely just due to the sizing I'm doing. Going any smaller than a delta of 0.004 at the shoulder would likely give me extraction issues. Perhaps using a bushing die to not size the neck as much would help, but I'm only going from 0.341 fired to 0.333 sized. It's not huge difference.
I've got a Cortina Precision expander die that is being adjusted by them to allow the 30cal neck to enter unharmed. That die will definitely size my web down properly, at least it did on my 3x fired Lapua.
For now, I think I'm going to use Cortina's die to remedy my issues. I'm uncertain about having another die made right now ($300!) because I'm uncertain of the future of these reamers. They could become 30-284 shehane , or straight 30-284. The presence of the SAC modular dies and Cortina's dies makes my 40* shoulder and owning a resize reamer kinda dumb. I could go with a 30-284 shehane, have the same case capacity as now, and just be able to get a 284 shehane die from SAC or Cortina with the correct bushing for 30 cal. No need to call a million smiths about getting dies made with my reamer (it's more expensive and less common than I thought).
Cortina's machinist, Clay, said it may be possible to do a 40* 30 cal bushing for their 284 shehane die for my current chamber. That might be a good way to go. If I decide in the future to change my chamber reamer, I can either get a different bushing made or sell the die to a 284 shehane shooter.
Maybe I'll have an answer for myself by the time I burn this barrel out. I'm only at about 600 rounds on this one.