I was really excited to see the M30 drilling represented in the game, and then rather disappointed to learn that its unique role as a multipurpose weapon was left unexplored. IRL this gun had 3 barrels, each with a different function. One shotgun barrel was intended for slugs, one for shot, and the third barrel underneath them was actually a one shot rifle, which could be used after pressing the button behind the locking mechanism and switching to rifle mode. This let the rifle barrel be used, and also popped up more substantial iron sights.
As it is now in game there are three barrels, and the button for rifle mode seems to be present, but it can’t be used, and the weapon ends up feeling practically the same as the TOZ-b, but with somewhat different stats. I’m fairly sure the technical implementation would be very similar to how grenade rifles operate, and it would really make the gun stand out more without making it enormously more powerful.