Terminology questions..

[Razor]

OK.. time to admit my ignorance...:confused:
Will you fellas explain to me in nub-ese...just wth is"throat" ??
You know, like in 'chamber throat' ?
I have a general idea what is meant , but...
Just EXACTLY where is this measurement taken ?
How do you take it ?
Why is it important ?

#2
"NOSE "
(No, not the pointy thing between my beady little eyes)
Nose as in like the nose measurement on a CB...
(same questions)

#3
Driving band...vs..whatever the rest are called.

#4
lube groove vs. crimping groove..
How do you tell the difference??

I realise this is old hat to everyone else but please bear with me and don't snicker too loud..

Thanks

Razor

[Pepe Ray]

Razor'
Obviously you need a Lyman Cast Bullet hand book OR a Lyman Reloading Manual( any vintage). If you can't afford new (I've been there) the preowned stuff can be found in many places.
Your question beget more and the Lyman Manuals are "the" reference books.
Pepe Ray

[leftiye]

On a revolter, throat is the part of the chambers at the front of the cylinder where the boolit rests (or should), in a rifle chamber throat is also known as freebore and is supposed to be groove diameter with the rifling cut out (lotsa throats in rifles are whatever size/shape they are). This dimension as to length can be SAAMI spec, or whatever someone made it depending on the person who chambered the gun.

Nose is the pointy thang (or not) on the front of the boolit, sometimes called the ogive on j-word bullets. The measurement you are describing is the cylindrical portion (IF ANY) of the nose, usually in bore riding designs. Nose = part of boolit in front of crimp position or groove.

Driving band= any groove diameter portion of the boolit. There are some who don't call the portion ahead of and behind a crimp groove driving bands, I do.

Loob groove, the recesses between the driving bands, can be found in various shapes.

[Razor]

Thanks for the info fellas..
You've been a great help.

I have the Lyman and the RCBS cast bullet handbooks...
I will reread them in greater detail this time..
(CRS don't help)

Razor

[Buckshot]

OK.. time to admit my ignorance...:confused:
Will you fellas explain to me in nub-ese...just wth is"throat" ??
You know, like in 'chamber throat' ?
I have a general idea what is meant , but...
Just EXACTLY where is this measurement taken ?
How do you take it ?
Why is it important ?

In a rifle, the throat is the unrifled portion of the barrel between the chamber mouth and where the lands begin. Another valuable term is LEADE. This is the area of rifling (lands) that begins at the end of the throat, and extends to the point where the lands attain their full height. Just to make it interesting some may use leade for the combination of the throat and leade, but they are different places with different features. The pistol throat was explained.

#2
"NOSE "
(No, not the pointy thing between my beady little eyes)
Nose as in like the nose measurement on a CB...
(same questions)

On a cast boolit, the nose is generally taken to be that area forward of the front drive band to the end of the boolit. If the boolit design has a 'Dirt groove', or what looks like a lube groove ahead of the top drive band, the nose begins forward of it. Some pistol boolit designs mimic jacketed bullets, as in a TC (Truncated Cone). The nose on these begins at the turn of the ogive, or non bearing portion.

#3
Driving band...vs..whatever the rest are called.

Drive bands are the major diameter portion of a cast boolit, and are the parts that are engraved by the lands.

#4
lube groove vs. crimping groove..
How do you tell the difference??

Er ....... well a crimp groove designed as one, and intended to be used as one is usually about half the width of a lube groove. It is also generally tapered down toward the nose and has an abrupt ange at the front. Some designs in both rifle and pistol boolits don't have a crimp groove for various and sundry reasons. In that case you might crimp into a lube groove, or taper crimp into a drive band, or crimp over the leading edge of a drive band.

I realise this is old hat to everyone else but please bear with me and don't snicker too loud..

Thanks

Razor

You didn't ask, but I'll add for my own benefit (as it's a pet peeve) and this is Bore, Lands, and groove. All three terms have to do with features inside a barrel. For some reason when someone says, "I have a 30-'06 and it's bore slugs .309", that just irks. It just isn't right, and is not right on a very basic level.

Lands and grooves are distinct and totally seperate parts. Now BORE is correctly used in only 2 instances. One is to describe the measurement from the top of one land, to the top of the opposite land, or another way, it's the minor diameter within the barrel created by the cutting of the grooves. The second way BORE may be used is when describing the ENTIRE interior surface of a barrel, as in, "The bore of my rifle shines." This includes both the lands and the grooves.

The groove is exactly the dictionary definition . It is a narrow area where material has been removed from a surface and lies at a lower level. In saying, "My groove diameter is .308" describes the major internal diameter of the barrel, from groove to opposing groove. Or as an imaginary circle drawn perpendicular to the axis of the barrel and touching the bottom of each groove.

Thanks for the indulgence :-)

..................Buckshot

[paul edward]

"Driving Band" has it's origin in Artillery, where a copper or bronze band is pressed onto a Bore diameter steel projectile to grip the rifling.

[joeb33050]

Here's where I am on the drawing for the book.
joe b.

[Ricochet]

That drawing doesn't describe every rifle's "throat," alas.

[mike in co]

THROAT
See Leade (Lead).

LEADE (LEAD)
That section of the bore of a rifled gun barrel located immediately ahead of the chamber in which the rifling is conically removed to provide clearance for the seated bullet. Also called Throat or Ball Seat.

[montana_charlie]

I believe "throat" describes everything ahead of the 'chamber' that is involved in transitioning from that chamber to the rifled bore.

I would re-label Joe's drawing, as shown, to name the three segments of the throat he created.

However, I think most freebores are cut at groove diameter, in which case there would be no 'taper'...just freebore and leade.
Some throats have a smoothly tapered section instead of of a cylindrical freebore.
In that case, the throat would consist of a taper and the leade.

I think it's very unusual for a throat to have both a taper and a freebore...usually one or the other.

Then comes the fact that some barrels are cut with nothing resembling freebore or taper, meaning the leade starts right at the end of the chamber...as described in the definition of leade posted by mike in co.

That's the way I understand it...anybody else see it this way?
CM

[Ricochet]

Yeah, like you said, Charlie.

My K-31 is one of those with the leade starting straight off the chamber.

[Razor]

WOW !!
This is GREAT !!:bigsmyl2:
This is exactly what I was looking for..
Thanks a million..Everyone !
I'm gonna create a folder and save this..
Err....Has anyone thought of maybe creating a stickey/lexicon/dictionary thingee where the knowledgable ones may define relevant terminology for us "knowledge-challenged" ??:idea:

I really appreciate the responses..
Thanks again..

Razor:castmine:

[mike in co]

I believe "throat" describes everything ahead of the 'chamber' that is involved in transitioning from that chamber to the rifled bore.

I would re-label Joe's drawing, as shown, to name the three segments of the throat he created.

However, I think most freebores are cut at groove diameter, in which case there would be no 'taper'...just freebore and leade.
Some throats have a smoothly tapered section instead of of a cylindrical freebore.
In that case, the throat would consist of a taper and the leade.

I think it's very unusual for a throat to have both a taper and a freebore...usually one or the other.

Then comes the fact that some barrels are cut with nothing resembling freebore or taper, meaning the leade starts right at the end of the chamber...as described in the definition of leade posted by mike in co.

That's the way I understand it...anybody else see it this way?
CM


so whats the diff between taper and throat ???

most benchrest reamers have a freebore/leade and a throat( the tapered section). the freebore is in terms of inches as in 0.000" to 0.060" and throat is described as an angle as in 1.5 degrees or 1 degree 30 min with a distance from bolt face.

may i suggest that if you want to discuss such terms, you contact a reamer manufacturer, and ask for a blank drawing. JGS's is labled in a thru z and you just fill in your deminsions. there is
a lead(v) and a throat(w) clearly called out.
there is no labled feature that seperates the end of leade and the beginning of the throat .....
there is a transition from case neck to leade, but it has no special name.

mike in co

[felix]

Mike, yeah, if I were a reamer man, I'd surely provide a diagram with MY terms for the user to fill out. It is very difficult to visualize what someone is talking about without some "feel" for that particular person's intentions in advance. This is no different than using the terms "clearance" and "headspace". I can see clearly the idea of having a curving throat having a continuous set of angles. Wouldn't make much difference after a 1000 rounds anyway. ... felix

While we are at this labeling exercise, why is a church key called that? Must be a key to some church down at the brewery, eh?

[Char-Gar]

Razor... As you can see, there is no uniform terms. A throat is also a freebore, unless it is a ball seat? Got that!!

Felix... I have always surmised that a bottle/can opener was called a "church key" as a backhand joke. They used to pitch an opened in with every six pack of beer you bought. Most churches were anti-beer so, the opener was called a "church key".

[felix]

Yeah, Charles, my point exactly. Headspace versus Clearance equates to Chruch versus Beer. Amazing how such inferences get distorted without using EXACT definitions (and sentence construction). ... felix

[montana_charlie]

may i suggest that if you want to discuss such terms, you contact a reamer manufacturer, and ask for a blank drawing. JGS's is labled in a thru z and you just fill in your deminsions. there is
a lead(v) and a throat(w) clearly called out.
I do have some chamber drawings (though not blank ones) and one of them is even from JGS.
I have noted how JGS uses the term 'lead' and it is apparent their use does not even match the definition you posted earlier for the same term.
Therefore, I believe they use it incorrectly.

In your 'leade' definition (which I agree with), the rifling is cut away with a 'conical' tool, which creates the 'ramps' that lead up to the full height of the lands.
That can only exist in the forwardmost portion of the chambering cut, which is immediately adjacent to the actual bore.

Any area shaped differently (if one exists) can only be located between the 'leade' (ramps) and the chamber (cartridge case). If that zone is cut cylindrically, freebore is a good desctiptive term as it provides an area which the bullet is free to lie in - if it extends out of the case mouth a considerable amount.

The reamer makers have different meanings for the terminology.

Clymer uses 'throat angle' to name the area that JGS calls the 'throat'. (This zone exactly conforms to your 'leade' definition.)

Clymer uses the 'freebore' term to name the area that JGS calls the 'lead'.

Your posted definition indicates that JGS is the more incorrect (of these two makers) in the use of 'throat terminology'

CM

[Bret4207]

Do not start another "headspace" type pissing match. It's over with, so agree to disagree and move on.

[joeb33050]

The drawing Is from a short description of "included angle" in the book. After seeing this on the CBA site and here, it is clear that there's some differences in what we think the words mean. It's time to get a little dictionary put together concerning what's in the back end of the barrel.
The words include, but aren't limited to:
CHAMBER
BALL SEAT
FREE BORE
LEADE/LEAD
THROAT
BORE DIA.
GROOVE DIA.

So tell me what they mean to you, and what words are missing. We can get this done!!!
Remember, nobody's "right" on language.
joe b.

[tomf52]

Buckshot - Where you an educator of some sort, school teacher, whatever? Your delivery of explanations is as good as it gets. Clear, precise, and to the point. This is in reference to your bore and throat answers and many other topics to which you have replied. Yoy should write a book about casting and shooting. Thanks for your help. Tom

[joeb33050]

Here's what we've got so far. Nasty comments will be disregarded, unless I like them. Looking cor a competent drawer.

NOTE: Montana Charlie's modification of my (lovely) drawing is included, but invisible, here at "CHAMBER", "FREE BORE", "LEADE" and "THROAT" since the drawing defines these terms.
A drawing or picture would clear up many of the differences.

BALL SEAT
The cylindrical section of the barrel cut just in front of the cartridge case
Ball Seat is the same as free bore.

BORE (DIAMETER)
The as-made diameter of the bore of the barrel, in .30 caliber, nominally .300"
Now BORE is correctly used in only 2 instances. One is to describe the measurement from the top of one land, to the top of the opposite land, or another way, it's the minor diameter within the barrel created by the cutting of the grooves. The second way BORE may be used is when describing the ENTIRE interior surface of a barrel, as in, "The bore of my rifle shines." This includes both the lands and the grooves.
Bore diameter - the diameter of the bore at the top of the rifling lands.


CHAMBER


FREE BORE
In a rifle chamber throat is also known as freebore and is supposed to be groove diameter with the rifling cut out.


Free Bore - the portion of the barrel from the end of the chamber to the beginning of the throat that is free from any rifling.

GROOVE (DIAMETER)
The as-made diameter of the groove bottoms of the barrel, in .30 caliber, nominally .308"
The groove is exactly the dictionary definition . It is a narrow area where material has been removed from a surface and lies at a lower level. In saying, "My groove diameter is .308" describes the major internal diameter of the barrel, from groove to opposing groove. Or as an imaginary circle drawn perpendicular to the axis of the barrel and touching the bottom of each groove.
Groove diameter - the diameter of the bore at the bottom of the rifling lands.

GROOVE DEPTH
The distance from the bore to the bottom of the groove, in .30 caliber, nominally .004".

LEADE (LEAD)
That section of the bore of a rifled gun barrel located immediately ahead of the chamber in which the rifling is conically removed to provide clearance for the seated bullet. Also called Throat or Ball Seat.
Another valuable term is LEADE. This is the area of rifling (lands) that begins at the end of the throat, and extends to the point where the lands attain their full height.


Leade - the area of the barrel from where the angle of the throat begins to where it reaches bore diameter.

THROAT
The barrel from the end of the cartridge case to the place where bore and groove diameters are not cut.
I believe "throat" describes everything ahead of the 'chamber' that is involved in transitioning from that chamber to the rifled bore
In a rifle, the throat is the unrifled portion of the barrel between the chamber mouth and where the lands begin.
On a revolter, throat is the part of the chambers at the front of the cylinder where the boolit rests (or should), )
in a rifle chamber throat is also known as freebore and is supposed to be groove diameter with the rifling cut out (lotsa throats in rifles are whatever size/shape they are).

Throat - the section of the barrel that begins at the point where the rifling starts






joe b.

[Bret4207]

Buckshot - Where you an educator of some sort, school teacher, whatever? Your delivery of explanations is as good as it gets. Clear, precise, and to the point. This is in reference to your bore and throat answers and many other topics to which you have replied. Yoy should write a book about casting and shooting. Thanks for your help. Tom


I thought everyone knew- Buckshot doesn't actually exist. "Buckshot" is a computer program designed by a former KGB agent named Sergi Pxyklungtski who originally came over to our side while posing as a member of the USSR national Womens Foosball team. He defected in Bayonne NJ and worked for several years in a Top Secret ballistics research center near the fabled "Area 51" which is where he met Scrounger. The "Buckshot" program is an amalgamation of several otherwise useless programs which Sergi developed in an attempt to make it big in the mood ring industry. Sad to say he was a bit behind the curve and when Disco died, so did Sergis dreams of fame. As I understand it the programs were stored on punch cards in a storage facility near Dry Bones, NM and were discovered by a Troop of Boy Scouts doing a merit badge project involving the removal of several tons of old tires. One of the Scouts advisors was a young man named Al, yes, our own Dippity Al. Al was intrigued by the cards and managed to track Sergi down through an exhaustive search on purchase reciepts found with the cards. Sergi, now in his late 80's, helped Al transfer the programs onto a Comodore 64 computer in the early 90's. The program took on a life of it's own as other people such as Felix, Sundog, Carpetman, BruceB and the famous but missing Mad Mexican and Mouse joined into the hoax. Somehow, the program morphed itself into a crude form of artificial intelligence, sort of a "HAL" of "2001- A Space Odessy" fame, although without the malevolent streak. It transfer itself into a Word Perfect program and is now thougt to be residing in Al Gores personal mainframe, hidden in a recipe folder.

Amazing isn't it? Yet every word is true. I guess we can only wonder what "Buckshot" will eventually become. Perhaps a program to find the cure for a dred disease, or a way to pick the winning Lotto numbers, who knows?

Glad I could help clear this up.

[Scrounger]

Professor Buckshot

[floodgate]

Guys:

What many of you may NOT know is that "Bret4207" is a recently- retired (by popular request!) Senior Editor and fill-in writer for MAD magazine - he evidently now has TOO MUCH TIME ON HIS HANDS!

floosgate

[mike in co]

will anyone with a chamber drawing see if they can find a drawing with three titled sections that begin at freebore and a forward of that section. call them what ever you want, but in all my drawing from freebore forward are two things freebore and the leade/taper(from the grooves to the bore)

someone seems to be confusing ball seat with leade/taper. a riflle has one or the other not both. that was the error i was trying to point out in the drawing being discussed.

some (most) chambers have a dia reduction from the neck to something just above groove dia. this is not a SEAT as it is too large in dia to contact a std dia bullet.

mike in co

[montana_charlie]

Here is a drawing from JGS, Mike.
It is one they made up for me when I was thinking of a 'long freebore' 45/90 application.

As you can see, the area they label as 'lead' is actually the 'freebore', and the zone where the leade truly lies carries a label of 'throat'.

CM

[mike in co]

THANKS CHARLIE!
but nothing between the two( what ever we end up calling them..leade.throat freebore) ?

i'll admit i did not notice the poor choice of terms i/they used, i was looking for the mysterious third characteristic in the middle.



thanks
mike

[Char-Gar]

Bret.... I love it... You have a wonderful gift for humor and satire.

[Razor]

Chargar: Got it !!
Buckshot, Mike in co, et al; Thanks for answering so I can understand..
As for the rest of the definition discussion, I ain't no machinist so this is kinda deep for me.

Razor

[montana_charlie]

i was looking for the mysterious third characteristic in the middle.
Oh! That third thing was already there in the drawing I stole from Joe, so I had to call it something.

I think it's most comon to have a freebore and a leade...or just a leade.
I don't ever remember seeing a chamber (or drawing of one) which had three elements.

But, I am still convinced that 'throat' is the full combination of shapes (however many they are) found between the chamber and the fully-formed bore...even though the reamer makers don't seem to like that definition.

They (most of them) like to stick the 'throat' label on the leade portion of the chambering cut. It's kinda like they don't like that word 'leade'...like maybe it's too British, or something.
CM

[mike in co]

BALL SEAT
See Leade

THROAT
See Leade (Lead).

LEADE (LEAD)
That section of the bore of a rifled gun barrel located immediately ahead of the chamber in which the rifling is conically removed to provide clearance for the seated bullet. Also called Throat or Ball Seat.

FREE BORE
A cylindrical length of bore in a firearm just forward of the chamber in which rifling is not present. Associated with bullet jump.

YES THESE CAME FROM SAMMI.
I DONT HAVE A DOG IN THIS RACE, was more concerned with a 3 characteristic area when i was familiar with only two.


JGS definitley has one of the two wrong which ever way we go. i think saami is the way to go( is that news to anyone).
they have the freebore cylinder section as "lead"
the first characteristic would be "free bore"(saami clue the word "cylindrical"), and the second characteristic would be "lead"( saami clue the word "conically").

please note that saami says "lead" is also called Throat or Ball Seat.

thanks
mike

[KYCaster]

Open the bay door please, Buckshot.











Nah.....just doesn't have the right ring to it.

[Char-Gar]

Joe... Thanks for your efforts to codify this stuff. It may be like trying to nail jello to a tree, but it something that is needed.

[joeb33050]

Joe... Thanks for your efforts to codify this stuff. It may be like trying to nail jello to a tree, but it something that is needed.

I'll get this done and then you all will use my definitions or there will be TROUBLE!!! Ve haf vays to make you use der gorrect vord!!!
Or maybe not. The CBA guys are into this a bit.
Who will draw???
joe b.

[crabo]

This will make a great sticky if it ever comes to a consensus.