Thank you for contacting Beretta Firearms Technical Support.

Unfortunately, the manuals as originally written had taken into account various features that would have been available on the Army submission version of the APX. However, some of these features did not make it to full completion as the APX was not selected for the MHS program. At this time, there are no thumb safety or adjustable sight options as the manual may mention, however, they are still being considered by our product design team as a possible future upgrade. There is no time frame as to when this might occur.

Thank you for your inquiry.