The barrel is thinner than older trapdoor 45/70's  but as I was told by
 a gunsmith when I asked him that same question......Today's 
 metal technology is so much better than it was only 50 years ago, that
 the barrels don't have to be as thick, as for accuracy,  my 1895CB is
 more accurate in my hands  than shooting an 18 inch guide gun.  Makes
 sense.....as it is 8 inches longer.  Yes,  You certainly can shoot the same
 loads out of the  cowboy as you can the guide gun.   I guess I should 
 say to still use  caution and work up loads in each individual gun.