1more, on that episode of Gun Talk they used both. If you are looking to play with a suppressor, you might want to look into the .300 Blackout. My boys have just completed an AR each in 300 Blackout and they shoot great. Uses std AR mags and with a little time you can make plenty of 300 brass out of .223. Cut it off at the shoulder, run it through the sizer, trim to length. I'm thinking about building up one myself.
Larry