IMHO the 12x will handle the 190 just fine. This has been proven mathematically AND in the field. A very reliable twist/stability factor calculator shows over 1.4 gs. This is plenty. Berger Bullets recommends the 12x for their 190's which are longer than the SMK.
I use to run the 200 Nosler ACCUBONDS in my 300 with a 12 twist with 1/2MOA accuracy and never showed any signs of instability. Even in cold sea level air. You will need an 11x for the 208-210 grain pills.
That said, I would be ****ed that I spent what we spend on barrels and got one that did not match the specs that I ordered and would demand an exchange. But that is just me.
M