As far as not making brass for the 6.5x55 from 30-06 sized brass, it's mostly a fallacy.
When the huge influx of 6.5x55 rifles came into the country in the mid seventies, brass or loaded ammunition was long out of stock and production. There just wasn't any and no one would bring it in, neither in Canada or the US.
Those of us, lucky enough to have rifles chambered for this cartridge, had few choices. We could either pack the guns away, set back the bbls and rechamber to a wildcat, rebarrel to a popular cartridge orrrrrrr, make up brass from existing brass.
Now we had all heard of the great caveat of the 30-06 rims being a whopping .005in smaller than the 6.5x55 brass rims. Think about it for a few seconds, c'mon, it's not rocket science, .005in is nothing to really worry about. The lower pressures that the Swedish and Norwegian actions operated at were well within safety margins. There were untold thousands of rounds of 06 sized rimmed brass, such as 308Win, yes it's short but it does work well, 7x57, 8x57 and 30-06 were all used and another one, if you were lucky enough to be able to garner a supply was the IVI blank rounds used by the cadet corp and other military units for parade salute purposes. Just cut off the crimps and run through the sizer die. Good to go.
When the first new production Canadian made ammunition became available in the early eighties, the cartridges had 30-06 sized rims so I don't think that the normally overcautious manufacturers were to concerned about .005in rim dia differences. Of course, all of the brass made now, is of proper size, although I was given a few boxes of Privi Partisan brass that wouldn't fit in a shell holder, it was .010 to large at the rim, the base was ok.
bearhunter