No Mystery About The .240 Super Pooper
Q: In a previous article about the .243 and 6mm Rem. You mentioned the late Warren Page's .240 Super Pooper, but didn't explain how it came into being. Maybe you would like to tell us how it evolved?
A: The original .240 Page which was the forerunner of the .243 Winchester was made by necking down experimental Ordnance cases of the T-65 type to use 6mm or .243 diameter bullets.
It had a 30-degree shoulder and full 5/16-inch neck length. Winchester followed this wildcat with a commercial cartridge based on the 7.62 Nato or .308 Win. necked down, which was known first as the 6mm-.308, then 6mm Win. and finally as the .243 WCF.
Winchester departed from Page's suggestions regarding neck length and shoulder angle. The extra cost of drawing small calibre brass to steep shoulders and the desire to have the .243,.308 and .358 family alike in respect to neck and shoulder dimensions, led them to adopt the gentle 17-degree shoulder and short 0.241" neck of the present .243.
The later .240 Super Pooper evolved when Page decided that Winchester's version could be improved by a longer neck and a 28-degree shoulder angle.
Working with Fred Huntington of RCBS, he basically combined the body length, shoulder angle, and 5/16" neck length of the .244 Remington, fireformed it to have the body taper of the .243 Winchester and came up with the .240 PSP. A rifle in .243 or 6mm Rem. can be rechambered to .240 PSP for an extra two to five grains in capacity and increase in velocity of 150 to 200 fps. Page carried his original .240 PSP rifle to New Zealand where, shooting the 105gn Speer bullet at 3100fps he scored fourteen one-shot kills on red stags.