Shortest barrel possible?

[burnsome]

SBR project.....I'm wondering what the shortest barrel possible is that will function and stabilize the 6.5 G? Seems like the 300 BlackOut guys are running 7, 8, 9-inch 300BO's and recommend the pistol length gas tubes for functioning. I already have an 11-inch upper that runs fine with the carbine length gas system, but am thinking about a 7 inch project if its possible. anybody been there, done that yet?