Well, thanks for the reply....IMO, your clearance and sizing is too high, and I don't know about your annealing.
What you have is more like re-forming than normal bushing sizing.
Large angles are set in motion with excess sizing. This, leading to rolling of brass into forms different than expected.
I know Tubb is big into huge clearances. I had one of his 'roll Royce of dies' for my T2K in 6XC.
Worse die/chamber combo I ever ran into, as it plagued me with stuck cases. Basically big clearance chamber, super small die combo..
If I were you, even without this particular issue, I'd toss the barrel and Tubb dies, and start over with another reamer.