unerring russian

• безоши́бочный

  faultless, error-free, correct, exact

  unmistakable, unerring, infallible

• ме́тко

  accurately, on target, unerringly, with good aim

  aptly, to the point, neatly

• безоши́бочно

  unmistakably, unerringly, faultlessly, correctly