11 degree forcing cone questions.

[JellyJar]

I know that the forcing cone of a revolver is funnel shaped to help guide the bullet from the mouth of the cylinder to the bore of the barrel and that it is an important part for accuracy. In some advertisements for customizing revolvers as part of the overall job they state that they will cut the forcing cone to 11 degrees. This leads me to several questions:

1. What is the normal cut of most forcing cones.

2. If 11 degrees is better than the normal cut then why isn't it done at the factory that way?

3. Is a 11 degree forcing cone better then what ever is done at the factory?

4. Does recuting the forcing cone increase the BC gap?

5. Is there any way a 11 degree forcing cone can be bad?

Thanks

 

[ClemY]

Opinions on forcing cone angles vary. Some prefer 11 degrees, others 5 degrees (both due to the availability of forcing cone cutters from Brownell’s). Ruger seems to use something around 7 or 8 degrees. I think it is more important that it be uniform, smooth and concentric with the bore.

I formerly used 11 degree cutters for .45 and 5 degree for .357. Now I use 5 degree for everything. It is probably more a personal preference for me than anything else.

 

[dfariswheel]

It also depends on what bullets you're shooting.
Lead bullets are better with more tapered forcing cones, jacketed with shallower cones.

The factories use a cone angle that works well with all of them. 11 degrees might be great with a lead bullet and not very good with a jacketed bullet.

The critical dimension of a forcing cone isn't the degrees of taper, its the diameter of the outer mouth of the cone.
If the outer mouth is too big, accuracy is off. Too little and not only is accuracy off, the gun often spits bullet metal.
Measuring the mouth is done with a special plug gage that gages that outer mouth.
The difference between too small and too big is minuscule. That's why you have to use a plug gage, you can't "eyeball" it.