hfd,
You asked about shooting drills with your v1. There are an infinite variety of drills that you can use... That said, the most important, too me, is becoming intimately familiar with unholstering and holstering your weapon. As in, you need to get to the point where you can do this seamlessly and smoothly in either direction. This includes getting your dang shirt out of the way!
Also, in HKPro's MP5 classes, he makes us draw from a DA state when we have to transition to sidearm. If you are not used to making that first DA shot, you should practice!