Martel and Beams
Thats the problem, so many extra bits that confuse.
Martel was another item considered and possibly tested but never used in service. The AS12 was on the list but I never saw it fitted. Along with the beams and their vista tracks, the Nimtan Sights were also available but were rubbish. You could lock up the navs computer if you pointed the 2 vista tracks at each other, oh what fun on an 8 hr LROFE.
The on top sight was briefly tested but was considered too fragile, shame that could be useful for 126 photography, oh yes forgot about the cameras as well. Thats a long story, including a Whiskey, F135 the chigaco flash and Fincastle or was it Ayrd Whyte, can't remember.
You see you switched the nostalgia switch on!!