I asked this in a thread I started in Cast Bullets because it had to do with a cast bullet, but I will ask it here as well. Why do you have to seat a bullet with a longer ogive(man how do you pronounce that) deeper into the case than a bullet with a shorter ogive? I have tried to draw it on paper and it doesn't make sense to me. I am missing some key piece to understanding this.

Wes

The bullet with the longer ogive might stick in the lands and then pull out of the neck if the round is not fired. Such a seating might raise the pressure also or affect the COL magazine wise.

This applies for the most part to jacketed bullets. Some cast bullet designs are ment to have bore diameter ogives that are supposed to engage the lands. Also many cast bullets have a crimping groove that sets the seating depth.

WesN:

The correct way to pronounce ogive is:
"O-Jive".
This is the most frequent word that is mispronounceed during many conversations with fellow reloaders. I guess the second mispronounced is cannelure.

The ogive has to be seated the same distance from the beginning of the rifling in the barrel. The ogive is measured from the base of the bullet, so a bullet with a longer ogive will have a larger lineal measurement from the base of the bullet to the ogive. Since the ogive has to remain in the same place in relation to the lands, the larger distance on a longer ogive bullet will have to be pushed further into the case.

Usually, bullets with longer ogives are the heavier ones in those type of bullets. ie. a 140 TSX will have a longer ogive than a 130 TSX because they have to carry the bullet material further toward the tip in order to gain the extra weight. That's why if you have problems with fitting a loaded cartridge into your magazine, the heavier bullet will have a shorter overall length if you are seating the ogives the same distance from the lands.


Without guns we are subjects, with guns we are citizens

Ok let me elaborate and see if it helps make sense to my confusion. I have a Marlin 1895CB. I loaded my normal 300gr Sierra HP bullets in my normal Winchester cases, they are OAL of 2.525. I also recently bought some 300gr Meister cast bullets to try. I loaded 5 of these cast bullets as well. When done the cartridge with the cast bullets was overall shorter, around 2.490. The cast bullet cartridge would not chamber in my gun normally. I could get them to load, but I had to really jam the lever upwards to get them to. I went home and worked on seating the cast bullets deeper into the cartridge and that fixed the problem, but it still doesn't make sense to me. I think after reading woods post the light it starting to shine a bit though. So since the ogive is longer and the BASE of the ogive is what stops the bullet from going into the barrel any further. The longer ogive is trying to be forced into the barrel.

Ogive is a French word and in French it is pronounced oh-jeeve. As stated above the English pronunciation uses the long i.

quote:

Originally posted by WesN:
So since the ogive is longer and the BASE of the ogive is what stops the bullet from going into the barrel any further. The longer ogive is trying to be forced into the barrel.

When I am talking about ogive, I am referring (perhaps incorrectly) to the point on the bullets curve where it first reaches full diameter. From your referring to the base of the ogive, you might be thinking (perhaps correctly) that it is the entire curve that is the ogive.

It's all subjective anyway, and as long as we understand what we are trying to accomplish the semantics aren't critical. So the measurement of the ogive I am talking about is from the base of the bullet to the point on the bullet where it first reaches full diameter. So if that measurement is longer, then the bullet will have to be seated deeper. There are 3 points that remain fixed: the beginning of the rifling, the ogive (as I defined it above as the point where the bullet first reaches full diameter), and the base of the case. The distance from the rifling to the base of the bullet or the distance from the base of the case to the base of the bullet is not fixed and changes with different ogives. In other words, the ogive needs to remain fixed in relation to the beginning of the lands, unless you purposely change it.

In the instance you mentioned above, the Sierra bullet will have a longer curve and so the distance from the ogive to the tip of the bullet will be greater than the cast bullet. That's why the COAL will be much greater for the Sierra.

The most important measurement for your reloading is that distance from your gun's rifling to the ogive and that changes with each bullet, therefore COAL changes with each bullet type.

I have a Stoney Point Gauge and when I am going to seat some bullets, I remeasure for the seating depth and also chamber the loaded bullets to make sure they are seated deep enough.

Hope this helps and is not misleading.


Without guns we are subjects, with guns we are citizens

Hah, I think I am getting more confused. Inserted here is a picture of the two bullets in question.



The cast bullet actually has a shorter ogive, or at least I think it does. The cast bullet has a longer shank though. So am I having to seat the cast bullet a lot deeper because of its longer shank? It surely can't be the length of the ogive since it is shorter than the jacketed bullet.

okay....let me put this to rest. i went to the ever faithful dictionary and here is what an "ogive" really is:

"a graphic representation of a frequency distribution in which every ordinate represents the sum of frequencies in preceding intervals"

holy crap..!!!!!!!!! i need a beer..!!!!!!!

quote:

Originally posted by LeeOtis:
WesN:

The correct way to pronounce ogive is:
"O-Jive".

Weren't the O-Jive's a band back in the late '70's?

I thought I understood this until Bill Smith came along!

quote:

The cast bullet actually has a shorter ogive, or at least I think it does. The cast bullet has a longer shank though. So am I having to seat the cast bullet a lot deeper because of its longer shank? It surely can't be the length of the ogive since it is shorter than the jacketed bullet.

Hey Wes, It will help you considerably to understand that the issue is really about the portion of the Bullet that first makes the initial contact with the beginning of the Rifling(aka the Lead).

The confusing part here is you can have a "lead" bullet and we are talking about the "material" the bullet is made from.

But when you talk about the "Lead" inside the rifle, you are talking about the very beginning of the Rifling.
---

Now, what is happening is the Ogive on your Jacketed Bullet "Tapers the nose profile" so it can extend further into the Lead (aka longer Overall Cartridge Length{OCL}).

When using the "lead Bullet" and you try to Seat it to the same OCL as the Jacketed Bullet, the full diameter body portion of the lead Bullet (which will make contact with the Lead) is farther forward than the same "diameter" body portion of the Jacketed Bullet.

If you turn one of each around and Seat the Bullets in Dummy cases to just Kiss-the-Lands(where the Lead begins), the OCL will be nearly the same with those two specific Bullets.

Perhaps the diagram from the Stoney Point web site might help: http://www.stoneypoint.com/oal_photos.html

Thanks SBT

The diagram on the Stoney Point Site is where I understood the ogive to be

But, the definition in the manuals is the curve as WesN diagrammed.

So, back to your original problem Wes

quote:

Why do you have to seat a bullet with a longer ogive(man how do you pronounce that) deeper into the case than a bullet with a shorter ogive?

The ogive curve is not the determining factor in how deeply the bullet is seated, it still depends on the configuration of the bullet.

The following bullets give these measurements with the Stoney Point Gauge which measures from the base of the bullet to the point on the curve where the bullet reaches full diameter:

.308 cal 150 grain fail safe .595
.308 cal 168 TSX .726
.308 cal 180 TSX .813
.308 cal 180 Accubond .754
.308 cal 200 TSX .924

after subtracting 1" for the gauge.

Take for example the 180 AB and the 200 TSX. The total bullet length for the AB is 1.386 and for the 200 TSX it is 1.499.

But the measurement from the ogive (as Stoney Point diagrammed) to the tip of the bullet for the 200 TSX is 1.499 - .924 = .375. For the accubond it is 1.386 - .754 = .632.

So the Accubond has a much longer curve from the ogive to the point of the bullet, but the TSX will be seated deeper because the distance from the ogive to the base of the bullet is greater, ie. .924 (TSX) .754 (AB)

Hopefully this illustrates that the length of the curve (ogive) is not a factor in determining how deeply to seat a bullet.


I just reread this and I agree with bill

quote:

holy crap..!!!!!!!!! i need a beer..!!!!!!!

Without guns we are subjects, with guns we are citizens

Hey Wes quit worring about those awful French words (the French are awful anyway) and scientific explainations about a line drawn as a curve and all that. Just seat any bullet so it chambers ok and go on shooting no matter the shape. I can't pronounce the words so I don't worry about them and seat my rounds in good old American lanuage, "where they work best" Works everytime and don't have to say any nasty French either.