10" barrel
I don't want to blow smoke so I'll tell you what I know. I bought the revolver (at a legitimate gun shop), a leather (triangular) lined case with barrel pouch, the 10" barrel mounted, a 6" barrel and wrench to adjust the sights on the end of the 10" barrel (4 preset positions for the front blade) for $250. Both barrels are stamped Smith and Wesson, 44 magnum, the finish on both barrels matches the revolver perfectly. The long barrel measures 10.5" from crown to forcing cone.
I shot if for about 2 years and did not enjoy the long barrel so I had a smith who was a competitive silhouette shooter mount the 6" barrel and a 2x6 scope. I left the trigger alone because as it was it is the best revolver trigger I've ever seen.
I will say this I have 2 Smith and Wesson revolvers, this 44 and a model 10-5 in 38 special I'm 60 years old and have been shooting firearms before I could ride a bike and these Smiths have me spoiled.