English/US shot sizing

[Cold Spring]

I've often read that English (UK) shot sizes run one number less that US sizing but never tried to confirm that. That means. in effect, that UK #7 shot should measure like US #8's. Just recently I broke apart two shells from different boxes of the Gamebore shells shown in the pics. They're my favorite for grouse hunting in 20b vintage double-guns.

Shells are labeled 28 grams of #7. As many know 28 grams is a tad under 1-ounce and in fact that's what they weighed on my digital bullet scale. Shot averaged US #7.6 sizing and that's the average of 40 pellets taken from the two shells.

All this JFI.