Tried the same thing you have done. Sounds like you had good results. I did not have the same results and in fact just the opposite. Found out that the cyl throat diameter and bore diameter along with amt. of crimp the most critical factor along with the mechanics of gun and cyl alignment. I found that the Remington bullet miked out at .359-.360 whereas other wadcutters mike out around .357-.358. So by using the Remington pill for "my" gun just using the std flaring die in my 550 backed out so that it just starts the flare and then the "M" die I described getting the best resuilts. Unfortunately cant get sub 1" groups from the ransom, but getting one hole groups of 24 rds at 50 yds. In my experience need to have just enough bullet tension so you get consistant burn and didnt seem to get this with the custom flaring dies I had made up. I had .356,.357,and .358 made up like yours.Most bbls for wadcutters can run .355-.357 in diameter.Each cyl throat should be the same diameter & range to the center of bore, if the gun is too be accurate in my opinion.Would be nice to choose from more than one gun to check this out before building a custom gun.Twist is fairly important too, 1:14 being the one of choice for most. Some tout 1:10. Everyone has an opinion. What ever works for you is best.
Just wish I could shoot as good as the gun does