Colt .45 , "peacemaker" , for me, please.
I am not an absolute western fan ( but enjoy it like most fiction genres. Maybe among my 3 fav ones : Medieval Fantasy, Sci-Fi, Western. Not speaking specifically about writing genres) . I contributed with free work to a video game mod, some eons ago, I was indeed starting my 3D career (several companies' job experience came later, but back then had only worked in design/painting) . I still keep some pics/renders of that 3D (don't be too cruel, is for the machines of those years (maybe 20 years ago), the PCs could not handle many polygons, so, many concave areas and details are faked with textures, not with real polies or normal maps (those did not exist, yet...))
Other than that, the Dirty Harry's Magnum 44...
Back to classic westerns, the Winchester 73, and the Sharp Shooter, rarely depicted in any western movie... but was a fine (yet unreliable) sniper rifle of the times, all things considered.
Am not a fan of weapons, though... I have to research in EVERYTHING for both 3D and illustration projects... and end up falling in love with all what I research, lol (although being a pacifist and all... but have planned to model sth as complex as a tall ship in the line of the HMS Victory... just not that one, as everybody and their dog has modeled that one, lol... )
BTW, is almost impossible to find a single game 3D artwork where horses are both well modeled and animated... (just as rare as it is to see them well drawn in illustrations...)