I picked up a 992B military case with the following markings on the back:

U.S.
ORDNANCE DEPT.
WATCH - R.R. GRADE
MFR'S PART NO. 992B
SERIAL NO. OE-4912
HAMILTON WATCH CO.

What SN range for the 992B movement would be correct for this case?

-Steve

Not sure about the serial # range, but it would be correct with a US govt or US Army marked movement.

My 992B's case has almost the same text as yours, but with OE-7643. Its movement's serial number is 1198601.

Anyone have any idea of its approximate year of manufacture? (The watch is in really nice condition, and keeps great time.)

Torrence,
From the serial number you listed, it appears you have a 992 movement made about 1916-17. The 992B, which is an entirely different movement, was produced from 1940 to abt. 1970 and had serial numbers ranging from C001 to about C525000.

The first model 992L (lever set) movement was made in 1903 and continued until about 1914 when the second model was introduced with some changes.

The second model was produced from 1914 until 1931 when the (third model) 992E (Elinvar) movement was introduced. This new model had a solid balance wheel and Elinvar hairspring and was produced from 1931 until 1940 when the (new) 992B movement was introduced.

Robert

By gosh, you're correct. It appears that I have a 992 movement in a 992b case! [The movement does show 992, not 992b.]

Sorry to have posted misleading information.

Torrence,
No reason to be sorry. The purpose of this message board is to assist and share all the knowledge we have about watches.

You might consider becoming a NAWCC member.

Robert