With regards to Ian Flemming,
He was a member of the OSS durring WW2. The passage about a spy getting killed in Casino Royal is actually one of the assignments that Ian Flemming was sent on and completed in New York durring the war. The Japanese had set up a dummy business in New York City durring the war, and it just happened to be above the office that the British Government had set up to run the Government should England fall to the Axis. Flemming and a collegue went across the street to get a clean shot at the Japanese office, the collegue shot out the window, and Flemming took out the spy. This can be coroborated in the both the biography of Ian Flemming, as well as a the book "A man called Intrepid", concering the direct communications between FDR and Churchill durring the war.
So, Ian Flemming was quite familliar with firearms, and quite proficient with there use. That being said, he was first and formost a writer, so his list of other weapons could quite well have been just to add color to the story.
D