Anyone try one of these yet in an Uzi pistol or micro smg? I’ve tried the Pike arms one and they work great. They claim(pike) they are made to IMI spec? https://kakindustry.com/auto-and-semi-micro-uzi-barrel-threaded-9mm-4-25/
Have you checked the Parts , Accessories and Ammo section? It's a good place to start. Word of warning though, whenever you purchase something from another member, make sure you know exactly what you're getting and you both agree on the terms. Take a good look at the descriptions and images included first. Also, 16" mini barrels are kind of rare, I think Vector only made them for their particular carbines, but if you get one of the longer barrels, you could always cut it down.
You could also try getting member BarrelXChange to make one for you. He recently did a big run of them and only makes them intermittently otherwise, but maybe he can squeeze you in. See this thread: