No sniper can one shot to the body in a regular shot. If you use weapons of light, some high-impact snipers can one shot to the body. Highest-impact snipers can also one shot to the body at about 3 levels under with level advantages on. An example is a 34 shooting a Black hammer or Efrideet's Spear to a 31 in Trials of Osiris or Iron Banner. The only perk currently (6/3) that can make a sniper a one shot to the body is final round. Unless they add reactive reload or luck in the chamber, you cannot get a one shot sniper. The only exceptions are pre DLC snipers (LDR, Longbow synthesis, and Efrideet's Spear). Final round has been taken out of the game so no more one shot body kills, unless the exceptions from above are a part of it.