Pretty straight forward, always aim for his noggin At All Times to kill him easily

A High Damage Output contributes with helping you kill them with headshots. Also the higher the damage, the easier it would be for the armor on their helmet to fall off.
An example of guns with good damage output are:

• AK-74 (80+, both golden and normal)
  
• AMR-16 (80+)
  
• Thanatos 50. (3000+, 1 shot headshot)

On the other hand, a high Rate Of Fire also helps, but mostly it's only usefull on close quarters engagements with him.
And example of guns with good ROF are:

• Kobus 90
  
• Compact 5
  
• Heather SMG

Now what would make it even easier to kill them? Good Damage AND ROF. But guns with these two things are quite rare.
Some guns with good damage and ROF are (that i know of):

• AMR-16
  
• CAR-4 (Fully Modified)

Use Nades or Grenade Launchers to blow his armor off. This makes him a LOT easier to kill. Also, explosives stun him as well for a couple of seconds so then u can switch to your Dozer-Killing-Weapon-Of-Choice and kill him with ease.

You keep shooting him in the head,
His Helmet armor is gone,
His Visor is broken,
But even if u headshot him right in his soft-puny face, only Non-Flame nor Explosive can kill him with that "Final" headshot.
So heres a better strat:

1. Use Fire Or Explosives To Shred His Armor Off
   
2. Then Switch 2 Your "Normal" Weapon
   
3. Break His Visor (if its not broken alredy)
   
4. End This Story

Killing him in close quarters is much, much more easier than killing him at a longer range. Just dont aim down the sights. Just spray and pray. This is essentially better strat with guns that have a very high RPM but low stability.
Some examples of them are:

• Kobus 90
  
• Jacket's Piece
  
• Specops Submachinegun
  
• MAC-11 (dont know ingame name)

So in the previous section i said how it would be easier killing him in close range. Easier. Not Safer. Make sure to keep ya distance with him as close and as far as possible. Especially those ♥♥♥♥♥♥♥ Skulldozers and their OP Saigas.

So u decide to snipe the bastard instead (coward). But this is a challenge of its own. Good Damage makes killing him easier but Good Accuracy is also needed to make sure ur shots actually hit the bastard.
An example of guns suitable for mid-long range engagements are:

• Every Sniper Rifle
  
• Eagle Heavy Rifle (with long range scope, single shot)
  
• AK-5 (with long range scope, single shot)

Also i suggest using a Laser Attachment to make things easier.

1 Shot (or rocket i guess)
1 kill

Thanks to all those heisters that have helped me do all those heists i have done in my heisting career (even when theyre utterly useless, especially you mike).
Also, special thanks to Spypers who gifted me PAYDAY 2 In the 1st place.