This is the Corner Shot CSM, an amazing gun that will indeed shoot around corners. Watch the video below, it is leaps and bounds ahead of standard arms in terms of utility in a live situation.
And here is a video of it being fired. I think it may require some extra training (or just siting in…) though because the guy testing it didn’t seem to be able to hit his plates. But still, the ability to maintain the safety of cover while firing at the bad guys is a substantial advantage.