Hamilton Model 22 - gimbaled version question

I recently purchased two gimbaled M22's from a mid-west clock collector. One of the boxes has a key lock latch versus the more common push button latch. My question is how many key latch boxes were produced before switching over to the second and more common version? I understand the key lock version was modeled after the Nardin Chronometer the USN was purchasing before the war. In the mid 60's I was stationed aboard a USN destroyer that saw action in WW2, thus my interest. Thanks, Jeff

Hi Jeffrey. I do not know the answer and perhaps that is some of the vast amount of information that has been lost to time. Normally the specifications issued by the military are specific enough to limit the amount of variation by contractors in building the timepieces they are supplying, but then during war time anything is possible. One thought I had was whether the key lock box is original to the Model 22 mounted in it? I am not saying it is not, but given the number of repairs that would have happened over the last 75 or so years it has been around, things do get replaced and changed out. This was especially true during and after the war when there was little to no thought about collectors wanting things to be all original. Do you have any period references to M-22s originally being sent to the Navy with both kinds of boxes?