My first written guide ever! On Montana!

Welcome to my guide on the burly man who skipped leg day, the one, the only Montana! Now why should you play such a big mass of man you should ask? Well here's why!

Pros *Tanky (hailstorm and his mutation Icy Resolve along with Mansformation can make him virtually take a ridiculous amount of dmg)
*Minigun dmg is pretty damn nasty if managed correctly (Focused fire makes it a laser)
*Lumberjack dash is a great initiate/escape (Lumberjack blast only amps up the initiation potential)

Cons
Big hitbox Requires a fair amount of awareness to be a effective Going full dmg Montana isn't great (IMO, if you are, god help you) Mutations are necessary to unlock his full potential (lumberjack blast, focused fire, icy resolve are what makes him above average IMO). helix configuration With this configuration, we will be abusing the heatwave passive and the cooldown provided by hailstorm along with its dmg reduction. The point is to balance dps with tankiness as Montana along with some utility in the form of CC through lumberjack dash.
Level 1: Sure Go the Distance is great as an escape and initiate but I think its eh compared to Weather Man. Take Weather Man
Level 2: LumberJack Blast if not available, take The Ol' One Two. Why LumberJack Blast? Simple, it can go through thin walls and the squares in Meltdown to stun enemies through the geometry. It also can provide a multi-stun which can be stupidly effective against healer/tank combos or just annoyances like (insert battleborn character here).
Level 3-4: We ain't taking Gatling Grease or Firestorm. My reasoning is this, the spin-up isn't bad although in some occasions, it can really cost you a kill, so it may be a viable option but I prefer the additional hp at lvl 3 and The Cooler is chosen for obvious reasons that will be supported as I explain my thought process towards the end.
Level 5:Cold Blooded and Hot Blooded are great in their own rights (though I'd lean toward more aggression so Hot Blooded is a secondary choice), but once Focused Fire is unlocked, there is no contest to what helix choice is the best. Basically Focused fire at higher heat with the minigun grants less spread and allows you to more accurate than expected which makes Montana hit crits like nothing toward skirmishes of 3 or more enemy battleborn if you got decent aim and decent heat management. Now remember why I said The Cooler over Firestorm? If your minigun is about to overheat, hit Hailstorm to proc The Cooler which keeps your minigun heat at a sweet spot or 75-90% (also Weather Man adds on even more accuracy) which optimizes not only Focused Fire but your slow effect and your chance to land those sweet crits.
Level 6: Icicles isnt bad, nor is Feeling the Burn but really Swore Shield is the way to go unless you really want to output more dps with Feeling the Burn or hit more enemies with your hailstorm slow (Icicles) Personally I go with Swore Shield
Level 7: Icebreaker aint a bad choice but two more seconds for Hailstorm (Ice Age) offers far more reliable dmg than more dmg which can be hit or miss. Choice is yours in the end though, buddy.
Level 8: Too Big to Fail, "but what about Krackadown"? No, shut up.
Level 9: You know Bullet Buff and Perfect Storm are great choices but consider the previous helix choices before picking one of the two. However, if you have Icy Resolve take it for two reasons. One, Mansformation with Hailstorm dmg reduction is fantastic and two you will have an easier time surviving while putting out dps along with slows.
Level 10: Instant Payback No questions asked.

Summary
Montana is a character that requires a fair amount of awareness and timing which is funny considering how basic his kit sounds. A good Montana like a good player in general should do is be aware of the situation at all times. You see a person going way to aggressive? Pummel his ass against a wall and unload on him till he tries to get away. Then you pop Hailstorm and continue dishing dmg and slows till they drop or are super low. Teamfighting will rely mostly on your Mansformation/Lumberjack Dash. Learn to time your engagement and get on the enemy team's frontline. Remember however that even if you are a tanky SOB, you will be dead if your team does not focus correctly or you make a terrible engagement.
Why optimize Montana like this?
Well it brought me the most success with the character when I picked him up.
*Why The Cooler and Focused Fire?
Because when you are getting close to overheating you activate Hailstorm, abuse as much of the accuracy you get from your level helix choicse (see leveling) and you will still put out significant and accurate dmg. I disagree with you Well no shit! The game is still new and we are finding out new things as well go! All discussion leads to better choices and good build patterns. What gear do you use on Montana? mostly dmg-reduction, -CC reduction and his legendary gear piece since its special effect is good for what I'm building towards.

Conclusion Well there you have it folks, my build guide toward a champ I hated but come to love dearly, its my first guide I've ever written and I'd loved to hear feedback on what you guys think about it so I can try to write better guides in the future!
EDITED: Cleared up the format a bit thanks to your feedback! I appreciate it a lot!