Yea, that's your cookie-cutter MM build right there. What's the best you ask? That's hard to answer, as we all have different playing style and maybe that build doesn't suit you. However, that build is certainly the most popular and probably then that might arguably be the best build.
If you're an FPS gamer (First Person Shooter) like myself, you probably would feel right at home working on tactical stance build and a point into snipe (as I have). I built my MM to try and emulate my fps playing style and building my MM around that cookie-cutter build just didn't suit me. And perhaps this tactical build doesn't suit you. I do use mutli-shot, but I dont have any points in it. Rather, when I need to use it, I switch to other battle-set to activate multi-shot.
But I can tell you this, no matter what build you create your MM with, I must say certain skills are a must and probably should be maxed: Dead Eye, Ricochet, Reflected Shot, and Beacon. If you plan on modding your weapon with ignite or phase (or others), you might want to consider Elemental Beacon.
As for guns, the most popular is the fire automatic rifle (thermite, exothermic, fusion). I personally like cluster rifles, and use it as my primary weapon. But there's reason why that fire auto-rifle is popular, it has a high rate of fire; does fire damage, so you can mod it with ignite attack strength; it's quite accurate for a high rate of fire gun; and because of the high rate of fire, you'll have a greater chance of scoring a critical, and proc'in either ricochet or reflected shot, or both.