i wanna be a marine with my primary MOS as machine gunner and secondary as rifleman how long wud trainin take?

I think boot camp got dropped to 12 weeks, and machine gunner are both infantry jobs. You will learn both in SOI. At SOI you will go to ITB which is 2 months. I just left SOI about 2 months ago. Remember every Marine is a riflemen first, then whatever their MOS is.