Been watching the drama unfold for the past couple of days. Be nice to see some of that energy redirected towards working on solutions instead of complaining that this new brass from a different manufacturer isn't an "identical replacement" drop in for a caliber that typically uses fireformed brass from another brand...
I think FatBoy nailed everything I was thinking. Yes, it's different and might not be what you were expecting... but get over it and work things out or send it back for a refund if you're that unhappy. I don't consider $12 for a modified shell holder to be a big problem, and I also wouldn't expect to get away with not having to tweak loads after changing brass manufacturers given the variation in case volume especially when many Dasher shooters are running at, near, or slightly over design pressures; the brass changed, so reduce loads and work back up.
On a positive note, just got shipping notice from bullets.com for the modified redding shell holder... that was quick! One more obstacle down.
Also found that one of the shell holders in the assortment for my Sinclair priming tool fits and functions OK, I think it was a #3.
The thick case rim isn't an issue in my action, and if it was I'd simply hone a little off the extractor until it was no longer an issue.
The gunsmith received his reamer today, hopefully he can get my barrel spun up in a decent amount of time. I really want to start in on load development to see how things work. I do wish the reamer was spec'd with a 1.610 neck length and 0.273 neck diameter just for a little more margin for us "load and shoot" guys who don't want to neck turn but the current 1.605 & .272 dimensions should be OK based on the measurements of the brass I received. The only thing I'm really wondering about at this point is brass longevity... and if the brass has a decent life the 500 cases I purchased should last for at least a couple of barrels as I don't plan on loading to the absolute max. However, I will acknowledge that with my luck the rifle will have the best accuracy node at or just above the max... LOL!
At this point I'm just hoping the Redding 6 Dasher dies I purchased from Robert will work OK with the Norma Dasher reamer chamber dimensions. I know the seater die won't work as received from Robert (not enough neck length, so the neck of the brass would bottom out before the entire case body and shoulder is properly supported.) Thus the seating die is at the gunsmith who will run the chambering reamer into it to lengthen the neck portion of the die and correct that issue. I'm hoping the dimensions of Robert's FL die will play nice with the chamber dimensions of the bullets.com PT&G reamer and the brass. Hopefully I'll find out soon.