All things considered, I think it's safe to say that the further back they go the larger the margin for error.
The fact of the matter is that C14 dating has failed too many tests to be considered reliable.Charles Ginenthal deals with this topic in (1997) in pages 153-202.In dating of ancient Egyptian objects, C14 dates which do not conform with the accepted chronology are discarded as contaminated and not published, those that do, are published. Since there is no means of determining what is contaminated and what is not, other than its' support of the accepted chronological scheme, it amounts to nothing more than circular reasoning.Ginenthal (p163) quotes a Harvard professor: As an example of this, Ginenthal cites the results of a test performed by the British Museum on palm kernels and mat reed from the tomb of Tutankhamon, who supposedly lived in the 14th C BCE.The results were 899 BCE and 846 BCE, a discrepency of almost 500 years. In "The Pitfalls of Radiocarbon Dating," But as the method was refined, it started to show rather regular anomalies.alter carbon results my hundreds or thousands of years so if you replace impacts with plasma discharge does it still cause disruptions in the carbon date? Anyway it would be nice to know for my presentation. A meteor impact will, according to EU theory, trigger enormous electrical discharges of the same kind. Gamma rays discovered in ligthning storms (never mind their speculation, but note what they observed): Picture Of the Day that discusses dating issues: rays or electrical discharges could increase the percentages of C-14 ("radiocarbon") in living organisms.