Of the 5838 catalogued Greek New Testament manuscripts, how does one accurately determine the date of publication for each one? Aside from a few isolated examples, none of the scribes actually wrote dates of transcription on them. As with P46 (papyrus 46 of Paul's epistles - Ann Arbor, Michigan, and Dublin, Ireland), even professional scribes would generally just write the book name, page numbers, and the count of lines copied. (General consensus: AD 175 +/-25)
Even if the scribes included dates somewhere, how could P52 (papyrus 52 of John's Gospel, Manchester, England) be dated, when just a small fragment remains? (General consensus: AD 125 +/-25)
Since papyrus, parchment, and paper, are all organic materials, carbon-14 dating would be the first technique on most people's minds. The problem with this is that carbon-14 dating was traditionally destructive. Although newer methods have come about in just the past couple years that are not destructive, they can only determine the date of the writing surface - not the date of the text itself. This is problematic because papyrus and parchment were such expensive and rare materials that they were frequently "washed" and re-used, so there is a good chance that the text is actually 25-50 years newer than the writing surface. With this said, there is a good possibility that non-destructive carbon-14 dating will be used to re-date manuscripts, though.
With absolute dating techniques mostly unavailable for the manuscripts, that left relative dating techniques, namely comparison of termina (cut-off) dates and handwriting analysis (paleography). These techniques cannot pinpoint an exact year, but they can give a tolerable margin of error of +/-25 years for the latter and a few years in one direction for the former.
By @HullBreach
