I did the same comparison a few years ago. Pattern tested & chronographed half a dozen of each old & new. Almost identical results with both cartridges.
The Eley Grand Prix as a brand goes back to 1903. They were available in all shot sizes including solid slug and spherical ball and lettered shot from LG, SG, Spec. SG, AAA & BB. And all numbered shot sizes from 1 to 9 in the 1960's as in paper cases then moved to plastic in the late 60's with options of crimp closure or roll crimp. The lettered shot sizes were all roll crimp. Also in the 1960's they introduced the Grand Prix 'High Velocity' with a 1 1/8th. ounce load. They earliest plastic cases were smooth plastic and the ones you have were the ribbed plastic and I would think from the early 1980's. The Grand Prix brand also came in 28 bore and 16; the 20 bores were called the '20 Gauge' and never found in Gran Prix.
I love the old Eley Grand Prix, wish they still made them looking like this. More traditional. Where did you get them from? If you don’t mind me asking?
