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Discussion Starter #1
- what does the forcing cone do?
- does it re-direct some gasses back to the cylinder to ensure the cylinder and barrel are aligned?
- help me understand.
- thank you.











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The forcing cone is a feature of a revolver's barrel, to be found at the end which contacts the cylinder's chamber mouths.
It is, essentially, a short funnel shape, cut into the barrel's interior.
Its function is to compensate for minute misalignments of chamber-bore and barrel-bore.
As the bullet is propelled from the chamber in the cylinder, across the slight gap, and into the barrel, that bullet first encounters the forcing cone before it enters the barrel's rifling. Thus, the bullet has the space to straighten its flight, guided by the forcing cone's funnel shape, before entering the rifling.

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Discussion Starter #3
The forcing cone is a feature of a revolver's barrel, to be found at the end which contacts the cylinder's chamber mouths.
It is, essentially, a short funnel shape, cut into the barrel's interior.
Its function is to compensate for minute misalignments of chamber-bore and barrel-bore.
As the bullet is propelled from the chamber in the cylinder, across the slight gap, and into the barrel, that bullet first encounters the forcing cone before it enters the barrel's rifling. Thus, the bullet has the space to straighten its flight, guided by the forcing cone's funnel shape, before entering the rifling.

Does that help?

- yes thank you
- how is the cone able to take that continual abuse?
- is it a matter of the bullet being softer and the cone being harder?





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- yes thank you
- how is the cone able to take that continual abuse?
- is it a matter of the bullet being softer and the cone being harder?





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If the revolver has proper timing it really doesn't take heavy abuse because it lines up correctly when it locks up. That said one of the main things to look at when buying a used revolver is the condition of that forcing cone, the reputable sellers on places like Gunbroker always include a close up picture of the forcing cone for this reason. If you look at used revolvers long enough you will see forcing cones that have rough blasted edges. A good used revolver buying thread is pinned on this site.
A revolver with bad timing will shave lead or copper and spit it sideways which is another reason not to stand off the the side of a revolver when someone is shooting one. Even well built guns fed a steady diet of hot magnum loads like the hotter 125 grain 357 magnum will accelerate wear on the forcing cone but, we are talking 10's of thousands of rounds. Most guns today will last several lifetimes of steady shooting and by the time the forcing cone wears out your frame is probably stretched beyond spec anyway causing excessive end shake.
One of the reasons revolvers are so expensive compared to semi autos is they require final hand fitting for correct timing. Revolvers are tough guns but, they have their weaknesses like dropping with an open cylinder or people that flip the cylinder closed like some Hollywood dip. Both of those can damage the timing on a revolver by even very minor bending of the crane or locking problems by bending the extractor rod.
 

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Picture of the forcing cone on my S&W 27-2. Sorry the picture quality isn't great.
If you look close you can see a little cutting at the bottom of the bore where the rifling starts.

IMG_20191109_093538.jpg
 

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The forcing cone is a feature of a revolver's barrel, to be found at the end which contacts the cylinder's chamber mouths.
It is, essentially, a short funnel shape, cut into the barrel's interior.
Its function is to compensate for minute misalignments of chamber-bore and barrel-bore.
As the bullet is propelled from the chamber in the cylinder, across the slight gap, and into the barrel, that bullet first encounters the forcing cone before it enters the barrel's rifling. Thus, the bullet has the space to straighten its flight, guided by the forcing cone's funnel shape, before entering the rifling.

Does that help?
The only thing I'll add is that the barrel/forcing cone should not come in contact with the cylinder. There is a small gap there to allow the cylinder to move freely.

The only exception to that that I can think of is the old Nambu revolver, IIRC, the action pushed the cylinder forward against the barrel when the trigger was pulled, eliminating the barrel/cylinder gap during firing.
 

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You never want your fingers or other body parts near the cylinder gap when shooting. Very hot gas and occasional metal shavings escape from the cylinder gap when the round goes off. The faster the caliber and the larger the caliber, the more gas and flash. If the timing is off and a cylinder bore doesn't line up correctly with the forcing cone and barrel, you will get metal shaving.

My Ruger Super Redhawk .454 Casull puts out a large flame from the end of the barrel and a large butterfly shaped flame from the cylinder gap when I shoot Hornady 240 grain XTP ammo. It is visible in bright sunshine. At night, it is quite awesome. Most of my revolvers and ammo only show a flame at night when shooting.
 

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The only thing I'll add is that the barrel/forcing cone should not come in contact with the cylinder. There is a small gap there to allow the cylinder to move freely.

The only exception to that that I can think of is the old Nambu revolver, IIRC, the action pushed the cylinder forward against the barrel when the trigger was pulled, eliminating the barrel/cylinder gap during firing.
Nambu, the first name in how not to do it.
 

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You never want your fingers or other body parts near the cylinder gap when shooting. Very hot gas and occasional metal shavings escape from the cylinder gap when the round goes off. The faster the caliber and the larger the caliber, the more gas and flash. If the timing is off and a cylinder bore doesn't line up correctly with the forcing cone and barrel, you will get metal shaving.

My Ruger Super Redhawk .454 Casull puts out a large flame from the end of the barrel and a large butterfly shaped flame from the cylinder gap when I shoot Hornady 240 grain XTP ammo. It is visible in bright sunshine. At night, it is quite awesome. Most of my revolvers and ammo only show a flame at night when shooting.
Same with my 4" Python when shooting hot magnum loads, such as the 125 gr load mentioned earlier.
 

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...
- how is the cone able to take that continual abuse?
- is it a matter of the bullet being softer and the cone being harder?
Yes.


The only thing I'll add is that the barrel/forcing cone should not come in contact with the cylinder. There is a small gap there to allow the cylinder to move freely...
Supplementary Information:
When that gap is too large, the situation is called "end shake" because the cylinder can move fore and aft in relation to the frame and barrel.
The frequent result of "end shake" is that the cylinder will become very hard to revolve, after the first couple of shots.
In an "end shake" condition, the fired cartridge "sets back," and protrudes rearwards from the cylinder, rubbing against the pistol's recoil shield. The friction of one or two set-back cartridges will bind-up the cylinder, and make revolving it difficult.


...The only exception to that that I can think of is the old Nambu revolver, IIRC, the action pushed the cylinder forward against the barrel when the trigger was pulled, eliminating the barrel/cylinder gap during firing.
The Russian Nagant revolver also has this, um, "feature."
It was a Belgian invention!
And it's useless.
 

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The only thing I'll add is that the barrel/forcing cone should not come in contact with the cylinder. There is a small gap there to allow the cylinder to move freely.

The only exception to that that I can think of is the old Nambu revolver, IIRC, the action pushed the cylinder forward against the barrel when the trigger was pulled, eliminating the barrel/cylinder gap during firing.
I wasn't aware the Nambu's cylinder moved forward to form a gas seal but I did know the Nagant 1895 revolver did.

https://loadoutroom.com/thearmsguide/is-the-1895-nagant-revolver-a-good-weapon/

-snip-
When the hammer comes back, the cylinder moves forward and over the forcing cone creating a gas seal for more velocity and later, the ability to suppress (silence ) the gun. -snip-

I have one and some of the weird looking ammo plus the .32ACP conversion cylinder. Nice gun but so much extra complexity just to gain a few fps from the gas seal.

Edited to add:
M1911A1 beat me to it. I gotta learn to type faster.
 
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You guys are correct, it was the Nagant revolver I was thinking of, not the Nambu. I must be getting old, can't keep all those old guns straight in my head anymore I guess.
 
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You never want your fingers or other body parts near the cylinder gap when shooting. Very hot gas and occasional metal shavings escape from the cylinder gap when the round goes off. The faster the caliber and the larger the caliber, the more gas and flash. If the timing is off and a cylinder bore doesn't line up correctly with the forcing cone and barrel, you will get metal shaving.

My Ruger Super Redhawk .454 Casull puts out a large flame from the end of the barrel and a large butterfly shaped flame from the cylinder gap when I shoot Hornady 240 grain XTP ammo. It is visible in bright sunshine. At night, it is quite awesome. Most of my revolvers and ammo only show a flame at night when shooting.
My Ruger SR .44 did the same. I'm sure the flames licked out all the time. Didn't feel it at all while firing, but after a box of rounds there was certainly a layer of soot on the fingers of my left hand in which I cradled my right hand holding the gun.
 

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