Board Thread:Questions and Answers/@comment-25814349-20141204230843/@comment-5230978-20141205003516

None of them is more accurate than the other. Index vol 3 shows the arc in the eyes of Touma and the Railgun manga shows it in the eyes of Mikoto and Accel. There are only some minor differences in a few of dialogues of the Railgun version (call them retcons if you want).