"So as to not tip off counterfeiters, U.S. Mint officials are not disclosing what functionality the edge-notching provides or what other anti-counterfeiting enhancements have been introduced on the Reverse of 2021 releases." so, no idea. LOL. I'd say the notch is "as struck" and in the 6o'clock position on every coin and is done by the collar, so it should not only fit as a key exactly, but also not show signs of machining to remove it after the strike. in theory, if all sets were set up the same all coins of the year will have it in the same exact spot with no rotation, and it be the same size and smoothness. add to that if they move it each year, and it could be decently effective in identifying a counterfeit if you know the position it should be, or that spacing isn't right or is funny. the notch actually looks a bit bigger than one reed, so it could be also and odd reeding spacing off narrowly that cause the gap and doesn't follow a uniform pattern of highs and lows. to where much like a circle fits in a circle, a star or square won't fit right. this feature is why I don't think a mule is going to happen. I think extra care was used in the set up of the dies and collar that would have caught a type one die being inserted into a type 2 set.
Missing reed is in the collar. You get it at the 6:00 position by simply setting the dies so it is in that location. If they move it to a different location next year all the mint (or the counterfeiter) has to do is set the die rotation so the missing reed is in the right spot.
Indeed, my mistake. That would allow them to easily guarantee the missing reed location then, of course. And, I suppose, the same would be true for counterfeiters. I'm back to wondering how much deterrence this would actually be.
The upsetting just puts a proto rim on a blank turning it into a planchet. The third die (collar) does the edging at the time of the strike. So, with the die lined up with the collar, the missing reed will be in the same place each time. This is my understanding, but, as always, I am ready to be corrected.
Yup, looks like you are correct. My mistake. Unfortunately @Conder101 beat you to the correction. Edit: I can also confirm this in Step Five of: https://www.usmint.gov/learn/production-process/coin-production Which I skimmed before my post, but didn't read far enough into Step Five before making claims.
Great thing about the forum is regardless who answers first, when you have a concensus, you can almost take the answer to the bank. Such a great place for learning or even reminding oneself of things forgotten. Love this place