Mr Deer Hunter must be reading Wilkepedia incorrectly...

I looked up .280 remington...It says ( correctly) that the .280 Rem was introduced in 1957...It also says that in 1979 it was renamed the 7MM Rem Express in an effort to boost sales because of the success of the 7mm Rem mag... It also says that in 1981 it was RE-NAMED the .280 rem because thier ploy did not boost sales...

As far as the 50 BMG being based on the 30-06, I suspect that is a figment of someone's imagination...The only similarities between the two cartridges are that they are are both rimless, bottleneck cases, which could be said about perhaps a couple hundred or more cartridges.. The 30-06s similarity to the 8 x 57 and many other rounds that share the same case head dimensions is much closer...