8x57 is as stated many times above 7.92x57
there is also an 8x57JS this is a lighter load for older GEW88 mausers (as well as a few others that started life as Blackpowder guns) etc... the m48 will handle any 8x57 or 7.92x57 load ya can get for it.
7x57 or 7 mm mauser is a totally different beast, arguably one of the most versatile rnds ever used and was VERY popular in the USA for sporting guns for decades its still one of the most favorites in most other countries, ya will find this most commonly the chambering of M95 mausers such as the very collectable Chilean M95 as well as many other rifles, there has not been much if any surplus 7x57 available for years and when ya do find it it'll run ya closer to 8-10 per 15 as opposed to the $2-3 a box for 8 mm.
Also get ya a quart of surplus GI bore cleaner its the best and designed for cleaning after corrosive ammo usage, I've been collecting milsurps for over 34 years, ALL of them get a steady diet of milsurp ammo (I buy by the case not the 20 rnd box) and have been using GI Bore cleaner for all 1278 rifles for 34 years not one pitted bore in the bunch...
Ya might wanna get ya a case of 8 mm BTW as its starting to get a lil spars latelly.....