PLAESE NOTE, the "Riktpunkt 45 degree sight" is not a valid attachment for this achievement. Thank you z RagnaroK z for mentioning this!
Weapon: Thanatos .50 Cal Sniper Rifle
or Galant Rifle
Attachments: Suppressor and 45° Red-Dot Sight
Skills: Select skills with a boost on silencers and sniper rifle damage and accuracy
(see video for my tree)
Start up any heist and make it loud. If you have the Thanatos, try not to miss too many shots prior to beginning your chain of 10 kills, unless you have the ammo perks from the enforcer tree. The sniper rifle does not have a ton of ammo.
To toggle between your red dot sight and scope press
. You must begin your chain with a kill from the red dot sight. Meaning that your last kill of the chain will be from your original scope, so keep that in mind when counting. Other than that, it is just a matter of practice and patience while you go for this achievement.
For those who would like a visual of what is done, check out this video:
If you give me negative feedback, please let me know why so that I can improve on my solutions in the future