Not a answer to the question, but Parker marketed the 'Long Range' concept before Hunter Arms
An ad in the May 1922 Hunter - Trader - Trapper
Western Cartridge Co.’s 12g 2 3/4” 1 1/4 oz. 3 3/4 Dram Eq. ‘Super-X Field’ was introduced in 1922. Could Parker have been tipped off?

[Linked Image from photos.smugmug.com]

Hunter Arms upped the yardage another 20 whistle

[Linked Image from photos.smugmug.com]