On Fri, 6 Mar 2009 11:38:18 -0800 (PST), "
wrote:

I'm looking at a Regal-Beloit end mill, 3/4" dia. M-7

It is described as Cobalt but, when I try a search, it shows it to be
HSS.

Which is correct?

M7 is a high speed steel -- I don't believe it contains any cobalt.
M42 is probably the most common cobalt HSS.

--
Ned Simmons