this looks also like a common jaegerrifle https://auctionet.com/de/3899283-ein-schleudergewehr-aus-der-mitte-des-19-jahrhunderts

but the barrel have no front sight

instead the octagonal barrel is turned round and there is a bayonet stud underside. maybe the bayonet had the front sight? looks not like the best way to fix a front sight on a rifle with a double set trigger.