It could have/might easily have had one fitted. Either at the factory - incoming suppliers stocks permitting. Or in service. A defective Mk2 backsight could easily be replaced with a Mk1 type if one were on the shelf.
It could have/might easily have had one fitted. Either at the factory - incoming suppliers stocks permitting. Or in service. A defective Mk2 backsight could easily be replaced with a Mk1 type if one were on the shelf.