Benjamin J.M. Johnson has an article entitled 'Reconsidering 4QSama and the Textual Support for the Long and Short Versions of the David and Goliath Story' in Vetus Testamentum 62 (2012) 534-549.
The story of David and Goliath contains one of the classical textual problems. It exists in two versions: a short version in LXXB and a longer version in the MT. The question of priority has divided scholars and much scholarly ink has been spilt attempting to resolve the issue. In the discussion about the short and long versions of the David and Goliath story the witness of 4QSama has largely been ignored. The present study surveys all of the extant portions of 1 Samuel 17-18 in 4QSama where there is a variant between LXXB and MT. This survey shows that 4QSama most likely contained the long version of the story.
He cannot bring conclusive evidence as to whether 4QSama, the most significant Samuel scroll from Qumran, had the longer or shorter version of the David and Goliath story, but does show that at this point there are more agreements with MT, and that one cannot use the existence of 4QSama to insist that there's always a Hebrew text underlying variant Greek.