Rolland,
Thanks so much for posting that.
I am in wonder that the article has a line drawing of the 6,5x53R with the rim thickness noted as .049”, yet the actual article notes various period documentation for Dutch & Romanian ammo was standard .060” to .075” rim thickness.

It begs the question as to what part of the rim might merit noting measuring a nominal .049”? Could it be that the “modern” line drawing measurement was a “2 stage” measurement where the stated actual rim diameter of .049” is the flat parallel (and only .049”) then radiused from there back to the case head so that the real headspace part of the rim is .060”-.075”

Lost to history?

All I am “fairly” certain of is that a .049” thick rim is excessively thin for proper headspace in actual vintage rifles.....
- Mike