I looked on the SAAMI 2015 chamber drawings. From breech face to the specific reference point on the chamber shoulder slope, they call for 1.7947" minimum and 1.8047" maximum - so to be SAAMI compliant, there is 0.0100" difference minimum to maximum for SAAMI 7x57 chambers. For SAAMI compliant cartridges, the minimum is 1.7995" - minus 0.0070". The idea is supposed to be that the maximum size SAAMI cartridge will chamber into the minimum size chamber; and the minus size cartridge will fire and not rupture in the maximum size chamber. I have no clue what dimensions that European or pre-SAAMI makers used. If you truly do have .013" difference between cartridges that will chamber, then you will be above the SAAMI criteria - and Euro C.I.P. will have their published standards, which I do not have, and no doubt original German makers that were pre-SAAMI will also have their standards.
If you hand load is not an issue - you should be sizing your brass to fit your chamber - not really too concerned about anybody else's standard - is only an issue if you insist or want to use commercial made ammo from time to time - if made in North America, the ammo should (but does not have to) meet SAAMI criteria. If the ammo was made in Europe for use in a European country, it MUST meet C.I.P. criteria - most (but not all) Euro countries have that as law.
By the way - what you did or similar is done often, but is not really a measure of your rifle's headspace value - you are relying completely on whatever dimension that brass might be, and no allowance is made for anything compressing - you need to use a ground steel "GO" gauge, which will be minimum SAAMI length for the chamber that is what it was made to check - then can shim or whatever from there to find out how far you are past SAAMI dimensions, if at all. Basically same story for a C.I.P. gauge or a pre-SAAMI maker's gauging. For what you did, some people use masking tape layers or Scotch tape layers - probably a better idea to do 5 or 8 or 12 cases from more than one box of factory shells - but is all really depending on the brass maker to get it correct. The ground steel "GO" gauge is the correct way to do it - and completely strip your bolt - no internals on the bolt body, at all. Forcing the bolt closed is not really a measurement - need to "feel" when contact is made - is actually a moderately "delicate" thing to measure headspace - like one finger-tip pressure on the bolt knob when closing it.