Forcing Cone Question

[Fox Creek Kid]

A thread on another forum here got me to wondering if USFA cuts an 11 degree chamfer on their forcing cones at the factory? I'm betting not.

[Banjoman]

FCK,
We do cut our forcing cones at 11 degrees. 
Gary

[Fox Creek Kid]

Then my hat is off to you fellas!! That is outstanding!!    I will be buying your '75 Remmy. 

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[Kinda Sudden]

FCK,
We do cut our forcing cones at 11 degrees. 
Gary

In case Banjoman might still be lurking in these parts, has USFA done any R&D on the 11 degree forcing cone? Can you share your experiences with us as to how much difference in accuracy normally noted? What I am trying to find out is if there is always an improvement and if it is worth having a FC on a gun that already shoots good recut to the 11 degree taper. Aside from, "if it shoots, leave it alone."

[Fox Creek Kid]

I'm not Banjoman but I will throw my hat in the ring on this subject. The answer is unequivocally yes, it helps. Actually it is a 79 degree cut (90 degress in an angle of course) but has come to be referred to as the 11 degree chamfer. I believe Ruger uses a nine degree for jacketed bullets. I have NEVER seen a PROPER forcing cone job cause a revolver to shoot worse. At the least it will make the forcing cone easier to clean as it will be less susceptible to leading and gathering fouling on rough edges. At the most it can turn a lemon into a diamond. Example: I have a new revolver that shot groups 4" left & 3" high at 10 yds. before a "cone" job. After the job they were in the ten ring and dead nuts on. The bullet has to enter the bore from the chamber unimpeded and well aligned in order to be accurate. I do it to all my revolvers and so should you. 

There is a fairly newer type of this called "Taylor throating" that is even more interesting.

http://www.alphaprecisioninc.com/revolver/default.htm

[Kinda Sudden]

Fox Creek Kid,

Thanks for your input. 4" left at 10 yds corrected with a recut forcing cone. Obviously your existing cone was not cut strait or deep enough. Very useful information here. I would think that when the forcing cone is cut strait and recut strait, the point of aim shift would be minimal. The concern here since for the most part we are dealing with fixed sights are that a recut cone may require the revolver to be regulated again. If the revolver is not shooting on a very accurate level the recut forcing cone followed with the sights being regulated would be acceptable.

The kind of knowledge I am looking for from a manufacturers experience, would be that with all things equal, that is correctly cut forcing cones and with disregard to leading, is the 11 degree cut more accurate by what percent or is it just that decreased leading and the increased chance of cutting the cone strait with a 11 degree reamer leads to a greater number of accurate revolvers going out the door? You have to wonder, if the 11 degree forcing cone yields better accuracy or at least a greater amount of accurate revolvers, why isn't everyone using it?

[Fox Creek Kid]

Labor = money.

[Kinda Sudden]

Labor = money.

How so? There should not be any difference in money or labor in choosing a 11 degree reamer over a 5 or 18 reamer. It gets down to manufacturers opinion on tooling and what they intend to shoot in that barrel jacketed or lead.

[Ten Wolves Fiveshooter]

How Do Gents

           I remember reading an article about Ruger useing an 11 degree forsing cone on their new model Ruger Vaquero's, but I was not able to find out anymore information about it . If they are I sure would like to hear more about it.

                                         Ten Wolves

[Doc Sunrise]

According to Jerry Kuhnhausen's shop manual, in his opinion, early 1st gen Colts that have 25-30 degree angle should be left alone, as well as late 1st gen Colts and Early 2nd gen Colts that have 9-10 degree angles.  He also states that the best commercial forcing cone measurements are 11 dgrees for lead and 18 degrees for copper jacketed and hard cast bullets.

He states that overly large and deep cones are weaker due to thinner walls, and it permits excessive gas blowby and powder/lead vapor residue buildup in the cone and rear bore which is destructive to accuracy.

He also states that cones oversized and deep are usually done by commercial makers to make the cone large enough to compensate for bore/chamber misalignment.

He wrote the book so he gets my vote on he knows what he is talking about.

[North Bender]

I'd only add that I wouldn't expect USFA to contribute the substance of their R&D on the subject.  It sure is always nice to have Gary post an answer to such a specific question though.

[Kinda Sudden]

I'd only add that I wouldn't expect USFA to contribute the substance of their R&D on the subject.  It sure is always nice to have Gary post an answer to such a specific question though.

Good point. Can't blame me for trying though

[Doc Sunrise]

I agree completely.  Not many other companies try to answer questions for you, let alone be mindful enough to watch a forum post.  It is nice to know that they are doing what is supposed to be done and not cheating to compensate for poor quality.  Just another reason why USFA is the best SAA today.

[Sixshooter_45]

FCK,
We do cut our forcing cones at 11 degrees. 
Gary

I thought that the closer the bore axis is to the cylinder's chamber's axis, a smaller forcing cone angle would only be necessary.

By the way, do you know what tolerance USFA tries to hold on the bore axis to the cylinders' chamber axis, since you don't line bore.

Just curious, I think STI holds less than .001, at least that's stated on their website, and their forcing cone is only 3°, but then again it's not a beautiful USFA either.

[Doc Sunrise]

A good gun to compare may be a Freedom Arms .45 Colt.  I have one in .41 magnum, and it does lock up like a bank vault and shoots superb.  Their specs are the tightest I've ever seen.  It sure would be interesting to see where they are.