Schrader combination gun 16 ga+ 9,3x82R with a short rifle barrel
https://www.egun.de/market/item.php?id=19380122
shotgun barrel 70 cm , rifle barrel only 51 cm

this was an idea before the great war that never realy catch on. they realise it was possible to made the rifle barrel shorter for safe weight with a similar velocity, anyway enough for hunting the common game but most people don't like it for several reasons.