I don't know anything about the Standard Steel shot ammunition as it's not available here in North America. It looks like the Europeans are using the CIP over the S mark as well as the Fleur de Lys stamp.

Advice on Steel Shot

I have never used any steel shot in my shotguns to date. The North American steel shot ammunition appears to be too hot for use in light game guns. As LeFusil and Dr. Drew had pointed out to me in an earlier post re: using steel shot through an improved modified choke, was not to, that the recoil alone from high pressure steel loads would very likely damage either the stock and/or the action.

So was just wondering about The British Standard Steel ammunition.