The .308 Norma Magnum was superseded in popularity by a firearm that was released in what year?
.308 Norma Magnum:  While it appeared to have a bright future initially, it was soon superseded in popularity by the .300 Winchester Magnum. .300 Winchester Magnum: The .300 Winchester Magnum (also known as .300 Win Mag or 300WM) (7.62×67mm) is a belted, bottlenecked magnum rifle cartridge that was introduced by Winchester Repeating Arms Company in 1963.
1963