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The Husqvarna models that were modified from the 98 Swedish Mauser also have this flange (which was presumably copied from the later FN streamlined bolt sleeve that lacks the sleeve safety), but what the Husqvarna lacks is the internal gas collar in the receiver ring. That was also a patented feature of the 98 system, and among other things makes the 98 easier to rebarrel, according to gunsmiths, than any other bolt action rifle.
What Husqvarna did with what they called their "improved mauser action" (or 1640 action) was take the 96 small ring action and bring it up to 98 standards, but with modern (1950's) metallurgy. The result is a very strong action in a lightweight configuration. This action has a safety feature that the 98 lacks and that is both front locking lugs are solid. There is no split in one for the ejector.
