Examples of the barrels offered on the Colt 1878 hammer gun are here Tony
http://www.picturetrail.com/sfx/album/view/17067005
One can only assume the Twist barrels were requested by the purchaser.
Twist barrels were indeed usually found on lower grade guns, but quality Twist performed well in the 1891 Birmingham Proof House Trial, and pattern welded barrels are best judged by the overall quality of the
gun
https://docs.google.com/Doc?id=dfg2hmx7_22ddqshmdq