Pappy,
No, that wasn't written by me.
The loading data in old Handloaders was "pretty sporty" for a couple of reasons. First, Bob Hagel was a staff writer, and he was well-known for pushing the rifle envelope. In fact one of the editors from those days told me Bob bulged the chambers in at least a couple of barrels.
The other was they used a lot of articles written by readers, partly to save money by not paying the guys much. Some included data perhaps a little sportier than Hagel's.
Have also been told by people who knew Dave Wolfe that the old magazines never made much money, which makes sense, as paid circulation (the number of each issue actually paid for) averaged around 10,000 when Wolfe sold the magazine to the art director, around 1990. In general, a magazine needs paid circulation several times that in order to attract enough advertising to make a profit.
The guy who told me this (who started writing for the two magazines when Wolfe still owned them) said Wolfe made his living in other businesses, and published Handloader and Rifle so he could write off his shooting hobby purchases as business expenses.
