we have a proprietary twist rate in the barrel
Um, how in the world can a twist rate be proprietary?
It may be that they have a variable twist rate barrel.
That is, the twist rate at the chamber is nearly straight and increases smoothly down the barrel.
The theory being that this allows the bullet to accelerate in it's rotational motion as it accelerates in forward motion.
I'm not sure I understand or believe the math or the theory.
I've worked on packaging machinery that used varying pitch lead screws to smoothly accelerate open topped containers (cans) to minimize spillage. It's mesmerizing to watch.