I suspect JW Fil's got something in that a RB gun may not be particular about the coning due to low velocity. I also think that the higher the velocity, the more improtant a short crown is, meaning that if you ware pushing 1,800fps through 2,100fps, you'd want as pefect a crown as possible, not a cone. For tiny-charge, low vel., short range loads, I submit coning might not effect accuracy adversly.
In my .45 barrel a cone of only 1/2" deep, enlarged 50 yard groups by 50% - tested next day and hundreds of shots to verify. The original crown was good, and the cone was perfect as well. I was not impressed with the accuracy, BUT - the accuracy was still tighter than many people can get from their rifles no matter what the crown might be. I was using the accuracy loads for that rifle, 70gr. 3F and 80gr. 2F. If I had adjusted the charges some, the original accuracy may have returned. Any time you change anything in loading, you sometimes have to re-invent the wheel - start at the bottom and work your way back again to find the accuracy load.
For a hunting rifle, I think cones might be the answer as they do load easier - for a purly target-oriented rifle for rondy's, I think they are second fiddle to a good short crown.