It appears to be the Reference 332.401, described as 1/5 second with split action; maybe not this exact model, but pretty close.

Below is scan showing this model in 1963 Heuer catalog; yep, no need for "this year's" model for this mission . . . this old Heuer was up to the task!!

Jeff

: It'll Take a Serious Dig Through the C-Drive, but I am confident
: that I have decent photos of the actual stopwatch that Charlie
: Duke used . . . International Watch magazine wanted me to write
: an article on the stopwatch / timing / etc. . . . that was
: around four years ago, shortly after we discovered the John
: Glenn stopwatch.

: NASA archives are awesome; you can find just about everything
: relating to these missions. The archivist in charge of the
: watches and some other equipment was very freindly . . . she had
: great stories about the "watch guys" calling her all
: the time about the Speedmasters . . . she said that I was the
: first to really show much interest in this old Heuer stopwatch .
: . . funny how that works!!

: Jeff

: ++++++++++++++++++++++++++

: