forcing cones - why change?

[HawkEyeEarl]

I see the mention of changing forcing cones to 11%.

Why change them?
Why does ruger user the 5% or whatever they are in the first place?

Are there simply pluses and minuses to each?

 

[tek4260]

The 11 degree angle is a gentler taper than the 5 degree angle. It deforms boolits less and in my thinking is a bit easier on the revolver if there is misalignment between the throats and forcing cone.

 

[260 Striker]

HawkEyeEarl - I concur with what Hunter posted. I have read for many years that some manuafacturers ream forcing cones and leave cutting marks which also harms accuracy. Seems like some manufacturers use different angles but many custom builders and smiths have learned over the years the 11 degree angle is the best for accuracy and less bullet deformation especially with cast bullets. I have finally broken down bought the reamers and guages to redo my revolvers to the 11 degree angle. I did one Ruger so far and it is amazing how much smoother the forcing cone looks now. Haven't gotten a chance to shoot the gun for actualy results but the forcing cone has to be better now to guide the bullet into the rifling. Should also reduce spitting from barrel/cylinder gap too. This might be one of those changes that just makes the shooter feel the gun is performing better. Time will tell.

 

[axisofoil]

11 degrees is similar to the most ideal angle for compression of fluids. In the case of a firearm, lead and soft copper act as "fluids" when engaging the forcing cone and rifling.

"Most Ideal" meaning "least energy lost for a given compression ratio"

 

[HawkEyeEarl]

That seems reasonable now that I see it explained.

 

[Olsherm]

The idea has sold a lot of those reamers me thinks. I ordered one of the from Brownels once and the gauges all went all the way into the forcing cones on all my Rugers so I could not see how it would cut anything??Maybe I just did not know what to do??Or maybe my guns were already ok from the factory.According to the check gages they sent all were ok or maybe too big already.

 

[tek4260]

A lot is made about cutting them too deep, ect. Like I said earlier, I couldn't get the gauges to work for me either, so I simply cut till the old forcing cone was just "cut away" by the reamer. I am not sure what the problem with going too deep is considering many recommend a Taylors Throat.

 

[Rev60]

The 11 degree angle is a gentler taper than the 5 degree angle. It deforms boolits less and in my thinking is a bit easier on the revolver if there is misalignment between the throats and forcing cone.

Not sure at all that I understand this... The angle is relative to the bore centerline isn't it? wouldn't 5 degrees be the gentler taper?

 

[Jimbo357mag]

The 11 degree angle is a gentler taper than the 5 degree angle. It deforms boolits less and in my thinking is a bit easier on the revolver if there is misalignment between the throats and forcing cone.

Not sure at all that I understand this... The angle is relative to the bore centerline isn't it? wouldn't 5 degrees be the gentler taper?

More funnel effect for the bullet entering the barrel. Less lead spitting.

 

[SlickRS23]

So, would the 11 deg cutter be used to remove the 5 deg angle or blend into the 5 deg angle?
It seems to me that if you cut the steeper 11 deg angle you would have to go way down into the barrel to completely remove the shallower 5 deg angle?
Just thinking out loud here as I would like to try this on one of my guns.
Jeff

 

[Iron Mike Golf]

You remove the 5 degree. You don't want a compound angle.

I always thought that going to a shallower angle meant you needed to go deeper into the barrel, not the other way around.

 

[Rev60]

The 11 degree angle is a gentler taper than the 5 degree angle.

I'll try one more time: Wouldn't 5 degrees be the gentler taper?

 

[Iron Mike Golf]

The 11 degree angle is a gentler taper than the 5 degree angle.

I'll try one more time: Wouldn't 5 degrees be the gentler taper?

No. 0 degrees is no taper, like the cylinder throats.

It's not so much the slope of the taper as much as the diameter of the forcing cone opening. THe greater the taper, the wider the opening, give the same depth.

A wider opening can be more cast bullet friendly. Depending on the gun, going from 5 to 11 degrees can cure lead spitting out the barrel/cylinder gasp when shooting lead bullets.

 

[Rev60]

OK - I see where this is going. Thank you for your patience with me.

Yes. I clearly understand that for a given depth forcing cone that the 11* version will provide a wider mouth and hence less likely to spit lead under normal circumstances. For that similar depth, the 5* cone will be much less tolerant of misalignment. I also understand there needs to be a tolerance greater than bore diameter to accommodate for manufacturing variation as well as the variation designed in to a revolver's lock-up characteristics.

I suppose I had only heard of depth/length being an issue within the context of the forcing cone plug gauges where when one is using the appropriate one (matching angle of gauge-to-cone) it drops in too deep. Yes, it does mean the cone is deep but more significantly it indicates the opening diameter is overly large.

I hadn't realized though that the depth of the cone was a critical measurement. Immediately what comes to mind is this being greatly elongated in the case of Taylor throating.

 

[xtratoy]

I have never had the depth gauge. I just have the 11 degree reamer and the appropriate bore guides and eyeball my cuts to remove the factory forcing cone until I get the results I want.

 

[dlhredfoxx]

11 degress and deeper into the breech of the bore... aka Taylor throating... my most accurate revolvers are...

1) Line bored with 11 degree forcing cones
2) Taylor throated, or a derivative of this is Reeder's "maxi-throat" which is a similar "free boring" method...

For the revolver to achieve its absolute maximum accuracy potential, all 6 cylinders have to be perfectly aligned with the forcing cone... OR to a lesser degree an 11 degree forcing cone can help "align" the bullet center with the bore center before it hits the rifling "cockeyed"... Taylor or Maxi throating just gives it a more gentle and elongated taper as it enters the bore/before it engages the rifling... all of these approaches are merely bandaids for not having perfect throat/bore alignment... which I'm not sure ANY revolver ever has 100% +/- 0.000 that... which if it did would eclipse a humans ability to shoot it as accurately as it's able to be shot...

Sorry for my rambling... too much coffee, now for some Copenhagen to bring me back down...

 

[tek4260]

Also, Taylor or Maxi throating is a pretty cost effective way of removing frame constriction. See 2dogs posts over on singleactions about a cantankerous Smith 625 where he had it Taylor Throated.


Here is one that could probably use a reaming to 11 degrees. But, it shoots well enough and doesn't lead.

 

[Iron Mike Golf]

... and doesn't lead.

Hey, what's that Chore-Boy doin' back there, then?

Just messin' with ya!

 

[tek4260]

It will find lead that you can't see Notice there is no lead on it.

Before the chore boy

and after

Of course after as many rounds as it has fired, I doubt there is even anything resembling a rough spot in that barrel

 

[Pinecone]

Back in the 60's, I along with many other gunsmiths/shooters were seeing a lot of very poor quality control in revolvers coming out of just about all the gun manufacturers. "One" of the problems was very rough forcing cones. This led to lead spitting, deformed bullets, poor cyl/bbl alignment, etc. A lot of us came up with varying degrees of tapered reamers. Brownell's recognized the problem and contracted for reamers to be built in at least three different degrees. After a lot of experimenting, 11 degrees turned out to be a happy medium for generally good results. Today, you will still get arguments as to which one is more optimum. Calibers, loads, bullet types all have a bearing on the forcing cone. For this gunsmith, 11 degrees has worked well in most cases. It's the old six of one/ half dozen of the other argument!....................Dick