Jose Arcadio Segundo, in the meantime, had satisfied his wish to see a shooting. For the rest of his life he would remember the livid flash of the six simultaneous shots-and the echo of the discharge as it broke against the hills and the sad smile and perplexed eyes of the man being shot, who stood erect while his shirt became soaked with blood, and who was still smiling even when they untied him from the post and put him in a box filled with quicklime. (One Hundred Years of Solitude, tr. by Gregory Rabassa)
Can you substitute being shot with shot? If yes, isn't there any semantic difference? Since being is an auxiliary used for passive construction, I don't think there is some difference.