I've never seen a picture on here of a coned muzzle. The ones above are actually crowned, not coned. A cone is usually 1" to 2" deep, and starts at bore diameter at the top of the muzzle, and over the next 1" to 2" gradually gets tighter and tigher until the cutting stops at the tops of the lands.
The only first hand experience I've had with that system, was on LB's .40 cal. rifle. He could not load the normal working load I used in the crown shown above in my pictured post, which was a ball .002" larger than my rifle's bore, but same size as his + a .020" patch. Both rifles had similar square-type rifling. I think the onger tightening of the cone actually made swaging the ball and patch into the bore more difficult. I also found this to happen with a bullet reducing die I made, wherein the shorter radiused crown step made drawing the jacketed bullets easier. This seems to carry over into our guns with cloth patches and lead round balls as well.
I coned out two barrels for testing, for a depth of only 1/2" and 3/4" as described in the first paragraph. Both barrels doubled their group sizes to 1" to 1 1/4" at 50 yards, average. I spent an entrie day 1/2 shooting paper and changing charges, to no avail - my rifle's ability to group tightly had deteriorated. I do not like to see paper between any holes in the group. It's only 50 yards.
Before coning, and with the crowns shown, they both shot 1/2" average groups at 50 yards, which is literally stacking. I do not like coning due to my findings of lost accuracy, but some feel their rifles are more accurate after coning and that's OK, but not for me.