Browning Hi Power Serial Number Lookup Ww 2

FN began serializing the HP with the resumption of commercial production after WWII (1946/47) at serial number '1', and Browning began importation of the HP in 1954 at about s/n 70,000. Approximately and I do mean approximately 8,750 per year were made through 1954 putting your born date close to late 1950 or early 1951. Browning Hi-Power pistols were used during WW2 by both sides. Under German. Serial numbers for the Browning Hi Power. I have found one site with S/Ns.

Belgium Browning Manufacturing Dates

NumberBrowning high power serial number lookup
I recently purchased an Hi Power. The serial number is in the 289XXX range without letters. According to the Browning WEB site 1153XX ran into 1964 during which they later started adding the 'T' prefix.
The ringed hammer and single-sided thumb safety, I believe, are original which would mark this as a pre-MKII, pre-70s pistol.
It would appear the gun was manufactured in 1964, but it seems hard to believe the serial numbers would run from 115XXX to 289XXX, a span of 174,000 in less than a year.
The roll mark simply says F.N.Browning from what I can tell from the pictures, not Browning Arms or Fabrique National as on later Browning and FN guns (I will have the gun by Friday) and is white. I can't decern any other roll mark on the pistol but the pictures are dark. In addition the serial number is on the slide just under the ejection port. There may also be a serial number on the frame, I expect there is, but I can't tell where.
Finally, the seller indicate there was a C.M.O on the butt of he pistol. I don't know if this is aftermarket or signifies something having to do with Browning or FN manufacture.
Anyone have any information. Obviously when I receive the gun I can take pictures and see the markings for myself.
Here are the pictures I have which are not particularly helpful.
Any help would be appreciated.