The Gun by Philip K. Dick, Science Fiction, Adventure, Fantasy

The Captain peered into the eyepiece of the telescope. He adjusted the focus quickly. "It was an atomic fission we saw, all right," he said presently. He sighed and pushed the eyepiece away. "Any of you who wants to look may do so. But it's not a pretty sight." "Let me look," Tance the archeologist said. He bent down to look, squinting. "Good Lord!" He leaped violently back, knocking against Dorle, the Chief Navigator. But when they got there, nothing moved or stirred. Everything was silent, dead. Only the gun showed signs of life . . . and the trespassers had wrecked that for all time. The return journey to pick up the treasure would be a cinch . . .