Structured barrels are a relatively recent development and interesting in and of themselves. One of the main objectives is to eliminate barrel harmonics that distort accuracy. The article didn't provide much info on the structured barrel used to break the record, so here's some from the only company I'm aware of that specializes in making them:

https://www.thefirearmblog.com/blog/2019/07/30/tacomhq-struc...

https://tacomhq.com/structured-barrels/

The Engineering Behind a TACOMHQ Structured Barrel: https://www.youtube.com/watch?v=C-7LKQYtU48