luv2safari; All,
YES, I know what the Germans call the various sorts of "combination guns", both SxS & (less commonly) O/U, whether 2,3,4 or even 5 shots. = I simply didn't confuse the issue by using the (quite different from USA) German nomenclature.
Note: When I went to school to get my German hunting license in 1970, one of the instructors showed us a SIX barreled combination gun. - 2 rifled barrels over 2 PAIRS of "stacked" double shotgun barrels.
(VERY heavy to carry in the field, imVho.)
I'm GUESSING that it was "an experiment" & likely was "one of one".
WAFFEN BENNEWITZ in "K-town" describes all 2-barreled long-arms, with one rifled & one smoothbore barrel, as Cape Guns.
Also, 65mm is 2.590 inches.= I therefore believe that firing 2.75" American shotshells may be "hazardous to your health" = It may be OK & it may not, depending on how the maker bored the shotgun barrel.
(I stand by my advice to have the combination gun, by any name, carefully inspected by a smith that KNOWS older European firearms. = I regard firing any antique firearm, absent a through inspection, as UNWISE & possibly dangerous.)
yours, tex
