The mystery deepens.

I dragged out my 99 300 Sav. 24" bbl serial 73238X that was sold to me years ago as an R model.
It appears to conform to everything in David's book.
But unlike my prewar RS, the fore arm is held on with a screw fastened to a female dovetaill let into the barrel.
Clarification ?

Another thing I ran across is that the 99 wearing the T7 in his book has the mounting screws much farther forward than my RS or the one shown in old Weaver ad. The one in thge book also has flush screws rather than the knurled ones handscrews on mine and in the ad. Looks and carries better no doubt.