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Old September 22, 2013, 08:38 PM   #1
Cosmodragoon
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What do you call that little part...

I was trying to have an intelligent conversation on reaming a cylinder when I realized that I don't know what an important part/feature is called. I tried to look it up to no avail. It is the little lip that meets up with the cartridge in a revolver cylinder. It is the thing that is spaced particularly to control what length of cartridge you can put into the cylinder, stopping people from loading a .357 magnum round in a .38 special chamber for instance.

I think that this is the thing that is either moved up or eliminated when a cylinder is reamed to accept longer cartridges. (I'm not sure which though would love to know!)

Thanks again for furthering firearms education!
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Old September 22, 2013, 08:42 PM   #2
Jerry45
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The sholder?
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Old September 22, 2013, 08:44 PM   #3
BumbleBug
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Forcing cone?
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Old September 22, 2013, 08:49 PM   #4
RJay
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I always just called it the chamber step, is that correct? heck, I don't know, people seem to know what I'm referring too.
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Old September 22, 2013, 09:32 PM   #5
dogrunner
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shoulder/chamber step.......all samey same. That's what it be.

Though it oughtta bear mention that in some cheaper....read Spanish revolvers that look like S&W will have NO shoulder and thus one can stuff stuff that ought not be there.......there!
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Old September 23, 2013, 07:18 AM   #6
g.willikers
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Cylinder forcing cone as separate from the barrel forcing cone?
Probably a source of confusion, though.
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Old September 23, 2013, 09:56 AM   #7
45Colt_Man
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The throat.
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Old September 23, 2013, 10:28 AM   #8
F. Guffey
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cosmogragon, my pistol reamers have a stop that does not cut, my belted reamers have a shoulder that cuts the chamber for the belt. My bottle neck reamers do not have a stop shoulder, getting carried away etc., etc., that is for another day.

That does not mean the operator that knows what they are doing and has the ability to determine the length of the chamber before they start, after they start and when they finish can not use a stop on the reamer to control the length of the chamber 'FROM THE SHOULDER TO THE BOLT FACE'.

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Old September 23, 2013, 11:58 AM   #9
Nathan
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I'm no expert, but I know what you are talking about. A straight walled cartridge really doesn't have a shoulder per say, unless that is the term.

To me, it is really the chamber and throat junction, but that is too complex.

Looking online, makes me think neck?? Somebody must really know!

BTW. . .

Cylinder Throat - The area fit ahead of the chamber in the cylinder which aligns the bullet to the forcing cone of the barrel.

Forcing Cone - The area of the barrel that accepts the bullet and aligns any slight misalignment coming out of the cylinder to the barrel.
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Old September 23, 2013, 12:07 PM   #10
Claude Clay
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in a semi one says that the cartridge headspaces on its mouth...that restriction cut in the bbls chamber being conceptually the same as the one restricting a 357 from fitting in a 38spl cut cylinder.

perhaps call it a cartridge restrictor step or ring
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Old September 23, 2013, 10:36 PM   #11
James K
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I have always called it the shoulder but I think the correct term is "leade", which is also the term for the similar part ahead of a rifle chamber where the bullet sits when a round is chambered. In a rifle it is ahead of the throat, in a revolver it is behind the throat.

In a chamber, revolver or auto pistol, using a case supported on its mouth, the shoulder is sharp; in a revolver using a rimmed case, the shoulder (or leade) allows the bullet to transition from the case to the cylinder throat and then to the forcing cone and another leade before entering the rifling.

Jim
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Old September 24, 2013, 06:27 PM   #12
Bob Wright
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Always heard it referred to as the "throat."

There is always talk on the Ruger Forbum about reaming the cylinder throats. This throat must match, or exceed, the forcing cone dimension. Otherwise, an undersized slug enters the bore.

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Old September 24, 2013, 07:34 PM   #13
James K
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From what I have heard/seen, the throat in a revolver is the straight part right behind the cylinder face. I goofed a bit on the rifle analogy, though, and you are correct. Where the bullet sits before firing is the throat; the leade (pronounced "leed") is he sloping area "leading" into the rifling.

In general machine terminology a leade is a ramp or slope that guides something. Another use in revolvers is for the cut leading to a cylinder stop notch.

Jim
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Old September 28, 2013, 03:59 PM   #14
Bart B.
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. . .the thing that is spaced particularly to control what length of cartridge you can put into the cylinder, stopping people from loading a .357 magnum round in a .38 special chamber for instance?

It's the chamber length point in a .38 Special revolver that's 1.1630" ahead of the breech face that stops longer cases (.357 Mag, for example) from being chambered. Ahead of that point is the cylinder's forcing cone tapering at a 6.5 degree angle to the chamber throat.

Ahead of the cylinder's the barrel with its own forcing cone

Check the following page from SAAMI:

http://www.saami.org/PubResources/CC...ecial%20+P.pdf

Yes, this is the thing that is either moved up or eliminated when a cylinder is reamed to accept longer cartridges.
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