I seem to have been confused by Google. It's Sneferu's reign I'm interested in. Stadelman seems to suggest it was 48 years, and if so a source for that would be nice, and I see that Krauss suggests 30 years but that the Red pyramid started earlier than the 30th year of his reign. [cat.inist.fr] is the article if anyone can get it for me.
KRAUSS R. ;

Statistical analysis of dated documents from Sneferu's reign implies that the cattle count took place more often annually than biennially. Thus the 'twenty-fourth occasion of the (cattle) count', which is the highest date yet known for Sneferu and which exceeds the 24 years allotted him in the Turin Canon, cannot be equivalent to 45 regnal years but rather to about 30. On the basis of the dates preserved on blocks from the king's Red Pyramid, a model can be constructed to demonstrate that about eleven years were required for its construction. This period accords well with a reign of about 30 years.
Revue / Journal Title
Journal of Egyptian archaeology ISSN 0307-5133 CODEN JEGAAN
Source / Source
1996, vol. 82, pp. 43-50

Doug Weller

Director The Hall of Ma'at
Doug's Skeptical Archaeology site::
[www.ramtops.co.uk]