Benefits of a Pistol Caliber Carbine?

[MegademiC]

And in doing so you then you end up turning a rifle into a pistol caliber if you use subsonic ammo which at 10 yards is negligible from a suppressed 9 or 40 or 45. You only see benefit at distance if using a suppressed rifle. In most cases unless you use the Lehigh in .300 AAC, the pistol caliber will actually expand larger.

I never mentioned subsonic ammo.