This strategy is absolute Cancer because it works so easily. It is insanely effective and this post will most likely get down voted because players are afraid you all know about this. Which is retarded when they could simply balance the game.
Take a mosin.
Buy good ammo.
Get a good spot at choke points near the extracts of maps like Shoreline and interchange. Preferably with dark background. You can move into some of the stones and mountain walls when laying down. You will be almost invisible when done correctly. Don't take the obvious spots on top of hills. Take half way spots with hill/mountain in the back.
Bodyshots and headshots will usually one shot.
Easy gear. You don't even have to loot anything by yourself as the loot pinatas passing are already fully stacked.
Your risk is minimal but you can easily take out the most kitted pmc with a single shot. You can keep all healing and ammo in your secure so you will only lose a mosin if you die. As the mosins are shit cheap on the flea your risk is nothing in comparison to the wins when shooting a fully stacked pmc.
Also your risk is minimised because you already are at the extracts.