G'Day Fella's,

Just a bit of info, regarding "Which Came First".

According to my Vihtavuori reloading manual, 4th Edition;
The 8x57I, was first introduced in 1888 (with a bullet diameter of 8.08mm - 0.318").
In 1905 the 8x57 bullet diameter was increased to 8.2mm - 0.323" and renamed 8x57IS.
The 7x57, was introduced in 1892.

Further to the 8x57, it goes on to explain the following;
"To maximise the confusion the letter "J" is commonly instead of the CIP-approved "I" in many German speaking countries, an abbreviation of the German word "Infanteriegescoss" (infantry ammunition).
The 8x57IS is also know as 7.92mm Mauser or 8mm Mauser."

Hope that helps.

Avagreatweekendeh!
Homer