CA = Converted automatic. Class 12-3 prohibited firearm. A portion of the .30-06 rifles were made as selective fire.
The selective fire guns had a selector lever which dropped down out of the stock on the left side of the trigger guard, swung forward and back. If there is a clearance slot, and detents, fore and aft, the rifle may have been a machinegun.
Most weren't. Most were semi auto only. But they are around, worth checking.