Xausa

FN commercial actions with thumb cuts are mainly pre-WW2 ones, I think. Post WW2, FN gradually introduced the following changes:
- From 1946: Bolt handle redesign
- From 1948: Low scope safety, chrome vanadium steel barrels, solid wall (no thumb cut)
- From early 50’s: Receivers tapped for scope mounts, FN logo progressively removed
- FN Herstal magnum action (incl. 375H&H) from 1953 (FN Browning from 1960 only)
- From mid-fifties: New action bolt (Winchester 70’s style) and side safety
All changes did not occur overnight and models with thumb cuts may have been used later than 1948 in order to make best use of existing factory stocks.

I personally own a FN rifle in calibre 375 H&H that can be precisely dated to 1957, thanks to the Belgian proof marks. If I refer to the above list, my rifle has the new bolt handle design, the modified safety, the solid wall (no thumb cut)and the drilled receiver. However, although being dated 1957, it still has the FN logo, the M98 action bolt and no side safety. I bought that rifle second-hand from Joel Dorleac and it can be seen at the following link: http://www.dorleac-dorleac.com/arme/mauser-pirschbuchse-30-06-2/?lang=en

Louis