Thank you, Mr Doudna. However, I was uncomfortable with the consecutive neatness of two length markings of 27.5 inches & 27.6 inches respectively.
My suspicion remains that BOTH rods were marked "27.5", and that the original form looked like this------------
Then, at a later date, Lt. Day added the 276 (note the unusual gap between '27.5' and '& 276')--------------
Conveniently, the version that got sent to the WC contained not a hint of the decimal point in '27.5'