I have not worked on that rifle, but looked into same issue on sxs. Cowboy Action shooter sites have decent write-ups for "tuning" coach guns like Rossi and Stoeger. It seems the issue is that the hinging of the action is also compressing the main springs, so the action of hinging open is also "cocking" the strikers. Various "remedies" included polishing the hole that those springs work in - to reduce friction against the exterior of the spring, but the limit of the opening for hinge action seems to be related to length of those cocking / main springs. Brave souls apparently clip off/grind off coils to get their barrels to hinge open wider. I have just continued to swear at it, hoping those springs weaken with repeated use. When I get annoyed enough at my Stoeger, I intend to clip coils, but want to have a set of factory replacement springs in hand, since no "coming back" from taking too much off and getting weak hammer strike...
Edit: I should have mentioned that my double does not come up against a hard stop when opening - can grab barrels and open it further - can feel that am working against a spring(s), not against a protusion or a burr..