Norma Tipstrike .270 Winchester 140grIn 1925 Winchester introduced a . 30 06 case necked down to a bullet diameter which until then never had been used any British or other European manufacturer: . 277. The result was to become one of the most popular hunting cartridges in the world. When introduced it offered better long range performance than any other available big game cartridge. It was the favorite of the late gunwriter Jack OConnor who through his writing popularized the . 270