In addition to above, DW barrel system doesn't have a very common problem on many other revolvers; barrel chocking where it is screwed into frame. Marshall Stanton had excellent article how he fixed barrel constriction by firelapping, combined with opening cylinder chambers on something like .4525". groups shrunk dramatically, from almost 4" to 1.5". Unfortunately his website where are all those articles is inactive. Hope that somebody knows some of those archive websites where it could be found.
Another approach to eliminate barrel constriction is so called Taylor Throat. Some say no improvement, some say considerable improvement. Here is what Iowegan, gunsmith an moderator on another forum has to say;
"I have personally seen badly constricted barrels that would not shoot better than a 6" group @ 25 yards from a bench rest and after Taylor Throat reaming they would hold groups under 1". Post # 6 at
http://web.archive.org/web/20020606140647/www.sixgunner.com/dad/throat.htm
More here
https://www.google.com/search?client=firefox-b-d&q=taylor+throat+revolver .
Another, very interesting statement, that links Taylor Throat with Dan Wesson revolvers:
Sometime after this two friends, Ed Wosika of Hanned Precision and Bud McDonald took this idea and began playing with it. They experimented on several guns and confirmed what we had found. They had reamers made up to cut the throating in several different calibers. When they had finished most of the tests they took the results to Wesson Arms. Wesson Arms began testing, again confirming what we had "discovered". (I am sure someone, someplace, had already done something similar.) They contacted Dad and asked his permission to use it in their firearms. Dad had been befriended by Major Doug Wesson in WWII and thought, "What a neat way to repay an old favor!" He gave Wesson Arms his permission to use the throating system. In return they named it "The Taylor Throat". Today Wesson Arms offers it in their revolvers.
http://www.sixgunner.com/dad/throat.htm
It would be interesting if you check rear end of barrel on your DW revolver. If there is no rifling first half inch or so, it does have Taylor Throat, see scetch:
View attachment 1111553
That might be one of the reasons why Dan Wesson revolvers were so accurate.