You may have me on that. I didn't know 5.56 ammo was available in subsonic. However, mini-gun surely does not.And even so, you might want to check penetration characteristics and types of ammo. Home defense rounds are intended to not overpenetrate.
I was obviously joking on the mini gun. As for subsonic, 75 grain is available in 5.56. I keep that stocked for use with suppressor (as subsonic is really the only way to use a suppressor at close range for it to work as intended).
I've done tests on the 5.56 ammo I use at the range. The pistol ammo I use is all hollow point, and it's not going through anything but the perp.
And even so, you might want to check penetration characteristics and types of ammo. Home defense rounds are intended to not overpenetrate.