Welcome to the Forum, Rich...
Your 99 sounds like an EG made in late 1950. Its Lever Boss Code ("LBC") should be the inspector's number followed by the letter "B". Here's what my records show... the LBCs are shown in brackets behind the rifle's serial number:
B= 1950: 531909(15B), 5502xx(24B), 555436(?B), 561xxx(24B), 575495(21B), 572777(15B), 58021X(15B), 584xxx(15B)
The Lever Boss Code is a more accurate (but nothing is "for sure" with Model 99s) way to determine the year of manufacture. The Code is inside an oval which is located on the lower, front side of the lever boss in the rear of which is that part into which the lever fits and rotates.
You may need a magnifying glass to read the LBC because it and the oval in which it was stamped are both often stamped VERY lightly.
You've got one of the best quality, most desireable Model 99s... enjoy it. My 1953 EG in .300 Savage is literally a duplicate of your rifle.
My favorite hunting load is 40.8 grains of H4895 (max load is 40.9 grains) behind a 150 grain Nosler Ballistic Tip bullet sparked by a standard Winchester large rifle primer in "accurized" once-fired Winchester cases trimmed to minimum length with the round loaded to maximum overall length.
This load gives a very consistent 2635 fps with a velocity variation of just 3 fps (+1 fps/-2 fps) and regularly shoots 3-shot, 3/4 inch groups @ 100 yards. The H4895 is a Hodgdon "Extreme" powder meaning it isn't effected by temperature changes... a desireable trait in a hunting load that may be exposed to wide variations in air temperature.
Strength & Honor...
Ron T.
