So I'm a noob but if I understand the Tubb system and what it does are some magic bullets supposed to fix a throat that's .156" too shallow? Maybe I'm missing something.
They have a grit on them that is made to smooth out the throats and bore. If using just the lighter grit then you don't get much throat growth but using the heavier grit it can lengthen the throat. Read above in the thread about people using it. A smith using a throated is how I would go about it but the Tubb rounds can help.
And I agree you shouldn't have to pay to fix Ruger's mess up. You should call them first.