Am I correct in thinking that there was / is an "alternative" model that strongly resembles the classic Mauser charger?

Given the very similar head size, the clip for the Swedishicon 6.5 x 55 should work, ditto the one for the Frenchicon 7.5 round.

Back in the late 1970s there was a swag of French .30-06 ammo floating about. Some of it came in aluminium stripper clips. Those of us eccentric enough to be shooting both .30-06 and 6.5 Swede found that the "soft" alloy French chargers would also work with the slightly larger rims on the 6.5 Swede.

There are possibly still a few here, somewhere in the "crypt"; I'll have a bit of a dig.

Maybe some enterprising character could also make a 10rd "competition" magazine for the G / K 11 and K31icon. If it's good enough for Lee Enfields.....