So - reading through this - here are my thoughts.
1) i'm extremely impressed with the work here, especially without the whole shop set-up
2) Most likely *cringe* the disc wasn't etched. There's a ridge from paint and glue build up on the real gun, and it probably had a Michell Thorens pulley disc (like the imperial hats/belts) on there, as thats what was on the merr-sonn prior to the shop switching bottom frames.
3) Todds BB is meant for his base gun only. It's odd they sell it as a separate kit, without any help to tap your own Denix. I do think the real Mauser was built this way, as the "barrel inside a barrel" seems a little counter intuitive, for firearms sake.
4)I'm in a numbering mood tonight, sorry if this is a weird format :lol
5) also, I've seen a Todd kit where the booster didn't fit all the way in the flash hider. it has to be ground a hair smaller in diameter. That could be forcing your FH too far forward too!
Thank you. The disk etching is so slight, it could be covered easily with a thin (1/2 mill) disk and none would be the wiser. I'm glad someone chimed in and corrected me. I have read in other threads that the disk was cut in when I asked what others were using for a disk. Guess I should have kept asking or got a 2nd opinion. Lol.
So what do I need to fix this and install a proper disk. My thought is to use some 1/2 mill aluminum sheet metal I already have. I can cut the exact size and adhere it to the gun. This will both, fill and raise ever so slightly.
Thanks for stepping in when you did. It should be an easy fix once I know what it should be that is.
Kevin