score:3
According to FM23-95 Basic Field Manual, 75mm Tank Gun M2 (Mounted in Medium Tank M3), the amount of traverse to the left and the right, are actually 14° 0'. Turns of hand wheel to traverse through maximum travel (28°) is 25½. One turn of the hand wheel was 1° 6'.
Note that the link above is to a PDF which may download to your computer, but opens in Firefox directly in my own.
Upvote:11
The operator's manual for the tank is available from archive.org. The OCR quality is not superb, but sufficient to confirm the 15 degree left and right traverse.
See page 41.