Assumptions baked into the VMS carbon dating

[Koen G]

Eggyk, all I know is that people who know much more of radiocarbon dating than both of us combined, have determined the often cited date range. Michelle Lewis, hoping for a later date, consulted with an external expert, who confirmed that the conclusion is sound. Fashion matches very well with manuscripts produced in this date range, including the tail end in the 1430's and 1440's. Paleographical evidence of the last folio aligns well with the date range. 

Also, to the best of my knowledge, there is nothing in the manuscript that can only have been made after 1450. But of course, people will keep pushing for a later date. Everything that's earlier is already fair game, so an earlier date is not interesting.