Head Height Discussion

N

Nathan

New member
In another thread, we got to discussing “head height”, but it seems like a distraction over there. So here, thepoint is to discuss head height!

stagpanther said:
I read the reference; it is described as: "For starters, the best modern cartridges have a lot of head height. That’s the distance from the case mouth to the end of the magazine."

I take this to mean that it's purely a function/limitation of the magazine. Still a bit confusing, I think what they are really saying is that these cartridge designs reduce encroachment of the bullet shank into the case capacity, especially with newer high BC/SD bullets.

I give the hunter the benefit of the doubt that funny things come up in conversation during those campfire conversations.
Click to expand...

Yea, Joseph is a bit confusing here. I’m sure he knows the term, but is trying to describe it. It all comes from people have been increasing a chambers freebore since they noticed that the bullet was intruding into powder space. Obviously, mag length, action stroke and chamber all need considered….as well as available bullets.
 
Weird term.

I wouldn't even call it an increase in freebore. Freebore is a matter of throat (or "leade") geometry, which can differ between cartridges with the same "head height" (sic).
It is simply COAL minus case length.
Or, case length + bullet length - seating depth.

Many of these cartridges have not increased "freebore." Rather, they have changed throat geometry angles and lengths.
If you want true "freebore," look at Weatherby cartridges.
 
Freebore is generally considered the cylindrical part of the chamber beyond the neck area and before the taper to land diameter. Is that what you are describing?

Throat is generally the taper area beyond the freebore, but I think some folks say throat is the cylindrical area and the taper. Not sure why that is often confused.

Honestly, there are a variety of freebore lengths & diameters as well as throat angles. I’m not sure if anyone has found a best. I frankly like my bullet to have a calibers worth of engagement when it is 0.03” off the lands. I also want my freebore pretty tight like +0.0004….but since I don’t usually buy my own reamers, I get what I get.

Obviously, this ties to mag length and cartridge specs and pressure safety in magnums. For some reason, many companies have chosen long freebore for magnums to lower pressures. Not sure why this is required except I think ammo company’s were really pushing velocity limits to make the magnums look better than the +100-150 fps that they actually are! Then you mix in powder availability and lot matching and you get the 7 PRC debacle!
 
Using the glossary in my Hornady manual, "head height" is the portion of the bullet, from the bullet shoulder to the bullet tip.

It has nothing to do with the cartridge or how deep or far out the bullet is seated, it is a term referring to a section of the bullet, itself. It is a measure of length, from one point on the bullet to the tip. And this measurement will be different for every different weight and style of bullet.

It is NOT "how far the bullet sticks out of the case", though it is included in that distance.

"freebore" is the unrifled portion of the barrel in front of the chamber.

For some reason, many companies have chosen long freebore for magnums to lower pressures.
Click to expand...

Weatherby became famous for doing that with his rifles and cartridges. Most of them have about 1/2" of freebore. This means the bullet gets a significant "running start" before meeting the resistance of the rifling. Also the space for powder gas has increased by the time the bullet hits the rifling and this results in lower pressure (at that point) than barrels with shorter freebore.

This system isn't conducive to the very best accuracy (meaning the very smallest groups) but it is plenty good enough for big game rifles, and that's what Weatherby was making.

I have seen the term "bullet heads" and "pills" used to refer to bullets, but that was in non-technical writing from over a century ago. It was slang then, its out of date and out of use slang today.

Proof loads are still referred to as "blue pill" loads, because of the blue color on the bullet tip used to identify them (US) but its is also slang, and not the proper, official name for the rounds.
 
44 AMP said:
Using the glossary in my Hornady manual, "head height" is the portion of the bullet, from the bullet shoulder to the bullet tip.

It has nothing to do with the cartridge or how deep or far out the bullet is seated, it is a term referring to a section of the bullet, itself. It is a measure of length, from one point on the bullet to the tip. And this measurement will be different for every different weight and style of bullet.

It is NOT "how far the bullet sticks out of the case", though it is included in that distance.

"freebore" is the unrifled portion of the barrel in front of the chamber.



Weatherby became famous for doing that with his rifles and cartridges. Most of them have about 1/2" of freebore. This means the bullet gets a significant "running start" before meeting the resistance of the rifling. Also the space for powder gas has increased by the time the bullet hits the rifling and this results in lower pressure (at that point) than barrels with shorter freebore.

This system isn't conducive to the very best accuracy (meaning the very smallest groups) but it is plenty good enough for big game rifles, and that's what Weatherby was making.

I have seen the term "bullet heads" and "pills" used to refer to bullets, but that was in non-technical writing from over a century ago. It was slang then, its out of date and out of use slang today.

Proof loads are still referred to as "blue pill" loads, because of the blue color on the bullet tip used to identify them (US) but its is also slang, and not the proper, official name for the rounds.
Click to expand...
Thanks for the good, clear and understandable info.
 
>
> “bullet seating head height length.” This is a measurement from the head
> of the cartridge case to a diameter on the ogive of the bullet.
https://www.gunsandammo.com/editorial/shoot-better-improve-factory-ammo-accuracy/385257

In other words, this:
https://impx.hornady.media/ay7lhny3...90b3MvNTUyMGJ1bGxldF9jb21wYXJhdG9yLmpwZw.webp

This is something I've used quite a bit when seating close to the lands in order to get repeatable offset.
I've never heard it called "head height" however.
 
> “bullet seating head height length.” This is a measurement from the head
> of the cartridge case to a diameter on the ogive of the bullet.
https://www.gunsandammo.com/editoria...ccuracy/385257
Click to expand...

Yep, I read that. I also read the entire sentence which you quoted part of.

It says
The next variable that crops up is what I call “bullet seating head height length.” This is a measurement from the head of the cartridge case to a diameter on the ogive of the bullet
Click to expand...

Note the words "what I call"...

and note that the author's definition does NOT match the definition of bullet head height used in the Hornady manuals going back to at least 1980.

which brings up the question of whom to trust, an internet author who openly admits the term is what he calls it, or the definition of the term as found in the standard reference works for the past 40+ years??

I know which one I choose...;)
 
What is the bullet shoulder?
Click to expand...

The bullet shoulder is the forward most portion of the bullet shank, the point it which the bullet goes from being full bore diameter to tapering down to the tip.

The Hornady manual has a drawing identifying all the parts and names.

The base (and the heel) are pretty obvious, the full bore size section of the bullet (the part that is the bearing surface) is the shank. The point where the shank turns into the ogive is the shoulder. The entire curved/sloped/tapered portion of the bullet from the shoulder to the tip is the ogive. Tip is the meplat.

The bullet head height is a straight line distance measured from the bullet shoulder to the tip.

It has NOTHING to do with the case, case base, seating depth, or anything other than the bullet alone.

This definition is in the newest manual I have access to, published in 2021. It is identical to the definition in the 2007 manual and the 1980 manual I have. It hasn't changed.


...This system isn't conducive to the very best accuracy
Why's that?
Click to expand...

Ask the guys who "chase the lands" that. They believe (and not without reason) that bullets seated so they are very close to the lands (.002" or so off the lands) are more accurate. This seems true, but isn't always a possible thing to do with every firearm and ammo combination.

The half inch or so freebore "bullet jump" that Weatherby built into his rifles produced guns that were minute of deer, minute of elk accurate, most going around 1.5-2moa. or less and that was what he was after.

And I'm going to use the definition AND the method that
actually has some utility & relevance in today's world.
Click to expand...

That's fine, the definition I use (what Hornady uses) describes bullet construction, NOT any method of measuring, or seating bullets. That is a different matter, and if it has some utility and relevance for you in today's world, go for it. It has no utility or relevance for me, as I don't shoot for the smallest groups or most accurate load possible.

some of my rifles won't allow me to seat bullets just off the lands and still function as repeaters. Its not a system that can be used with revolvers, or most (if not all) semi auto pistols. I have some varmint rifles and some single shots where I could load to just off the lands, but I don't bother, as the loads I have, loaded to, or below SAAMI max length specs are more than accurate enough for me, and I don't shoot in competition where a fraction of an inch is the difference between winning and losing.

you do you, I'll do me, and we'll both be happy. Provided that when we discuss technical aspects we all use the same terms, the same way.

If we don't, valid points and information can be misunderstood, garbled or even lost and that doesn't benefit anyone.

Yes, there will be a test later....:D:D:D :eek:
or at least a surprise pop quiz! :rolleyes:
 
[Hornady Comparator dimension to ogive...] NOT any method of measuring, or seating bullets
Click to expand...
Oh but it is....
Head-Height-65-Grendel.jpg

Gives very precise distance-to-lands seating measure once established.

(Is that the test?) :cool:
 
That mess is a compact load record:
6.5 Grendel
123gr Sierra Matchking
VN540 Powder/28.6gr/Harrells' Measure set at 50.0
CCI-41 Primer/Lot C26S
Lapua Case (Alexander headstamp) 1st firing/36.5gr WaterVol
OAL 2.26"
Comparator to Ogive 1.679 ("Head Height")
Velocity (measured/chrono) 2,350fps
Temp 36 degrees
Firing Date: 01/20/2012
Load Date: 01/14/2012
Redding Seating Die

Very easy to read/replicate precisely/paste in record book.



It's an acquired taste.
 
The only thing that matters is that I (and likely many others) have been using "Head Height" as defined by
the Hornady comparator as a factor in loading for precision distance-to-lands for over a dozen years so far.

But also -- for most people -- "head height" is a term never heard of ... much less used ...for any practical purpose.
So this is angels dancing on the head of a pin for them.
 
The only thing that matters is that I (and likely many others) have been using "Head Height" as defined by
the Hornady comparator as a factor in loading for precision distance-to-lands for over a dozen years so far.

But also -- for most people -- "head height" is a term never heard of ... much less used ...for any practical purpose.
So this is angels dancing on the head of a pin for them.
Click to expand...
Head height, as Hornady defines it, I can see as being relevant to bullet design as being a somewhat easier way of saying "distance from base of ogive to nose tip/meplat." In terms of measuring how that is used to determine cartridge sizing for optimal performance in chambering (other than used to measure consistency between bullets)--completely irrelevant IMO.:)
Comparator to Ogive 1.679 ("Head Height")
Click to expand...
That is not how Hornady defines head height.
 
Last edited:
mehavey said:
That mess is a compact load record:
6.5 Grendel
123gr Sierra Matchking
VN540 Powder/28.6gr/Harrells' Measure set at 50.0
CCI-41 Primer/Lot C26S
Lapua Case (Alexander headstamp) 1st firing/36.5gr WaterVol
OAL 2.26"
Comparator to Ogive 1.679 ("Head Height")
Velocity (measured/chrono) 2,350fps
Temp 36 degrees
Firing Date: 01/20/2012
Load Date: 01/14/2012
Redding Seating Die
Click to expand...
Why not just buy a .270 Winchester?

You won't have to sweat all that bizarre and muddled up numbers.

Just buy a few boxes of shells and go out and shoot.

Relax. Have fun. End the hard work.

All this stuff was already figured out a hundred years ago.

:)
 
https://www.hornady.com/bullets/anatomy-of-a-bullet
If I look at this definition, “Head Height” has nothing to do with anything but the bullet. Not cartridge, not case. Just the bullet distance from forward end of bearing surface to the tip.

If I look at this next definition,
https://ammo.com/comparison/300-prc...designed the 300,length minus the case length.
Head height is .... the overall (cartridge) length, minus the case length: i.e., length of exposed bullet once loaded in a particular case/cartridge.

AND… if I look at this third definition,
https://www.gunsandammo.com/editorial/shoot-better-improve-factory-ammo-accuracy/385257
…measurement from the head of the cartridge case to “a diameter” on the ogive of the bullet. Usually, the diameter on that ogive would be (approximately the bore or rifling diameter) of the barrel. (Note: this is what the Hornady comparator measures – useful for seating to specific lands offset)

The first two are somewhat irrelevant to a rifle’s handloading.
The third is very useful.
 
well there can be n0 doubt that we all use a confounded language where you can use any diphone and pronounce it several different ways, depending on the word it is in. example "ou" pron"ou"nced "ou"t ab"ou"t d"ou"bt and y"ou" ! the last and most commonly used doesn't fit. so if we argue semantics ( which does have it's place of course ) we miss the point of the discussion, while i don't care if you call it a cat or a feline, it can still be skined, by removal of the epidermis. now if the entire point of this thread is to establish proper descriptive terms, and definitions, then we need to start with first usage and establish a baseline, before we go on to consider modern usage. don't you think?
 
You must log in or register to reply here.
Back
Top