After reading countless posts about forcing cones, hearing all sorts of conflicting statements, recommendations and opinions, it might be helpful to review what is actually known.
First, I would like to direct those interested DIY members to the Brownells info sheet that comes with their forcing cone kits. 76-200-152 is the number printed on the sheet, but currently does not show up on the Brownells site. This sheet covers more information than I have seen in one place about how to do it, why you are doing it, and how to screw it up.
As the info sheet points out, the f/c was developed to compensate for the fact that revolver chambers don't line up perfectly with the barrel. So, to avoid bullet deformation and even spitting out the sides the f/c helps direct the slug more politely into the barrel lands.
At this point we know what the f/c is supposed to do and why it exists in the first place. Only recently, as the sheet states, was a good deal of experimentation done by Ron Power as to the cone's effect on accuracy when changing the angle and depth using lead SWC ammo. So, for shooters who actually intend to use lead SWC ammo, go ahead and follow Ron Power's recommendations. Let me repeat one thing that almost nobody talks about: f/c depth. The info sheet talks about it, shows what is recommended, but does not explain the reasons behind it. However, it IS important. More on that later.
Then we come to the opinion department. The majority of people who post about forcing cones have cut their personal revolver or a small number of revolvers and reported that the accuracy was much better and leading was eliminated with such-and-such a f/c angle. Therefore, they claim that the angle alone is fully responsible for their great success. That thinking is flawed and here is the reason.
Taking Ruger revolvers as an example, most come from the factory in a very rough condition. They are full of gross shavings, burrs, and tooling chatter marks everywhere. Things get even worse in the f/c area. Now regardless of what angle (or angles) exist, a f/c cut with a hand drill with a 30-grit sandpaper finish is going to capture lead. Smoothing up that same cone with no other changes will take care of the leading problem. As to the improvement in accuracy - maybe or maybe not. One thing is for certain, any improvement in accuracy due to f/c angle (assuming that there is no gross b/c alignment problem) is going to depend upon bullet shape and material. So what is true for one bullet type will not hold for another.
Now what about f/c depth? Brownells thinks it is important enough to make special gauges (at $50 bucks each) to check it. They state that the rule of thumb is: f/c diameter at the rear should be no more than .020 greater than the diameter of the bullet. They even suggest that if the cone is cut too deep, you might want to set the barrel back and recut the cone. That sounds like a serious consideration to me, and I'd like to know a bit more on this subject myself. A makeshift gauge can be made with a fired case that is flared to the proper max. diameter.
Finally, if the f/c is cut correctly (using the .020" rule) at 5 degrees, it will be deeper than correct cones with larger angles. It will be impossible to cut an 11 degree cone of correct depth without creating a step from one angle to another. Sure you can cut until the step is gone, but your rear diameter is going to be much larger than the plus .020" recommended. Basic geometry, no magic. Since each Ruger f/c seems to be different, it may be possible to do the 11 degree cut without going too deep. It all depends upon what you start with. So, figure out what you've got first. Smooth up the existing 5 degree cone and compare the performance.
Let's get our ducks in a row, folks. Its truly amazing what can be accomplished by a little smoothing. Do you think the manufacturer is intentionally trying to make their revolvers shoot poorly? An 11 degree reamer costs the same as a 5 degree reamer. Just some things to think about.