Dave,300 Blackout is basically a .223 case necked out to .30 caliber.It was designed to allow the military to load larger projectiles into an existing brass.Advanced Armament Company developed it at the same time the 300 Whisper (same thing) was coming into being.
Lots of pluses to this round including the ability to load sub-sonic rounds. I became interested in it about a year ago and have done mucho reading up on it. Do some google on it and read. It is neat.
Imagine a 220 grain round at about 1100 FPS and inherently accurate. Great deer round with little recoil and lots of accuracy out to long yardage.
The Handi rifle in 300 Blckout looks like a toy.

Stan in SC

The more I listen,the more I hear....and vice versa.

45/70,it's almost a religion.

If you have to take a second shot then you probably shouldn't have taken the first shot.