I highly recommend that you stay away from the green/white boxed Remington 9mm ammo and also the Yellow boxed UMC 9mm ammo. They work fine in pistols but are not good ammo for sub machinegun use.
Both are dirty and underpowered and are likely to cause a runaway due to lack of power to push the bolt back far enough to catch on the sear.
I've had runaways with both of those ammo brands and glad I didn't buy a bunch of either of them even though they were fairly cheap in price.
I've had excellent performance with S&B 115gr, Wolf 115gr steel cased (which I've run tens of thousands of) , Magtech brass cased, Gecco, FMS, IMI, Igman, Winchester Value Pack, Hirtenberger L7A1 (that's the hot stuff), and of course my own reloads.