If you shoot the Vermin SMG using different firing modes and with and without a suppressor, you get different levels of recoil...

Tests:
Single Fire w/out suppressor-has recoil
Full auto w/out suppressor-very low recoil
Burst fire w/out suppressor-has recoil(same amount per bullet as single fire)

Single fire with suppressor-less recoil than without suppressor, but still has some
Full auto with suppressor-same recoil per shot as single fire with suppressor
Burst fire with suppressor-same recoil per shot as single fire with suppressor