Great question. According to the book 'Brigades of Gettysburg' by Bradley M. Gottfried
< The 20th Maine and 83rd Pennsylvania on Big Round Top did not leave their positions until about noon. When the brigade was reunited to the east of Cemetery Ridge, the line was arranged, from left to right, as 16th Michigan-44th New York-83rd Pennsylvania-20th Maine. Within a short time,the men found themselves in the teeth of the Confederate cannonade that proceeded the Picket-Pettigrew -Trimble charge. Judson (83rd Pennsylvania) recorded that "hundreds of the enemy's shells which failed to explode, flew shrieking through the skies... those striking nearer would plow a huge furrow in the ground, then ricochetting and leaping upward to the height of a hundred feet, could be seen whirling away." Losses were exceptionally small because the brigade took refuge behind the abundant stone walls. Some of the men strengthened the walls with added materials.
The brigade remained there until about noon on July 4, when it was thrown forward on a reconnaissance to ascertain the enemy's position. Not finding any, the brigade returned to Little Round Top, where it helped bury the dead.>