Naybe this isn't the best place for this topic, since it's more about cartridges than rifles, but I couldn't figure a more appropriate category.
Some cartridges have been extensively necked up or down to produce other cartridges. For example, the .30-06 begat the .25-06, .270 Win, .280 Rem, .338-06 A-Square, & .35 Whelan. .308 Win, 7X57 Mauser, and .375 H&H have all begat numerous other cartridges. My question is this: The 6.5X55 Swede has been around an awful long time, but I'm not aware of any standard, commercial cartridges based off its case (I imagine there are probably some wildcats). Why is this?