Late in the M40's career All manner of 3-9 Accurange scopes were used, in the field.
The M40's still at Crane have a couple of Widefields, some gloss black round objectives, some matte black round objective. Even different crosshairs.
One Greeny in the Badger collection has a thin cross hair with a target dot. This scope came right out of DRMO in the mid 80's
More than one old 2112 has told me that when the 40's were getting to the end, getting any scope redfield had that fit the rings and the power range were used.