You have said several things that make me think it is not a die problem but a setup issue.
1. Won't fit in another gun
2. Two different dies and same issue.
3. Die all the way down on the shellholder.
I would say you might be bumping the shoulder back too far and creating a very small ridge at the case/shoulder junction that actually prevents chambering.
Ask me how I know that is an issue sometimes when you put the die all the way to the shell holder.
Had it happen long time ago to me on first custom rifle and dies.
Back the die off one turn and start resizing a new piece of brass until it will just chamber and then measure.
You can use the skip otto shims from Sinclair to use one die for multiple rifles by measuring the fired cases and set the die up for the shortest case and then use shims for the longer cases. Cost is about $12
The Redding competition shellholders with .002 variation for 5 holders is another good way.