What is an Ogive?

[Tazlaw]

As I understand it, an Ogive is the slanty portion of the boolit from the thickest part to the tip. (Yes slanty portion is a technical term )
But why is it important? This is eluding me.

[StuBach]

One reason to consider, in an auto feeding firearm the ogive can impact how well the bullet ramps into the chamber when stripped from magazine.

[Hickory]

Ogive is the part of the slanty that is used to measure the distance to the rifling. "The bullet will be x number of thousands off the lands."

[Larry Gibson]

The "ogive" is important because it's shape;

provides smooth feeding of the cartridge from magazine into chamber

determines how efficiently the bullet flies through the air (ballistic coefficient)

can determine the efficient transition of the bullet from sonic to sub-sonic

can give or promote the desired terminal effect

[onelight]

Here is a pretty good definition. https://en.wikipedia.org/wiki/Ogive
In reloading this shape may dictate the OAL of a particular cartridge in a paticular barrel. Some shapes in certain chambers may have to be seated deep to chamber or the barrel would need DougGuys work to chamber at suggested OAL .

[Scrounge]

As I understand it, an Ogive is the slanty portion of the boolit from the thickest part to the tip. (Yes slanty portion is a technical term )
But why is it important? This is eluding me.

It's a combination of taper and curve. https://en.wikipedia.org/wiki/Ogive Nice little drawing of the 9mm parabellum there to illustrate, and a photo of the fuel tank on the space shuttle.

HTH!

Bill

[Scrounge]

Here is a pretty good definition. https://en.wikipedia.org/wiki/Ogive
In reloading this shape may dictate the OAL of a particular cartridge in a paticular barrel. Some shapes in certain chambers may have to be seated deep to chamber or the barrel would need DougGuys work to chamber at suggested OAL .

Darn, beat me to it!

[Dapaki]

But why so many different curves to an ogive? I have a dozen .30 cal boolits that all have a different ogive but have the same base and very close weights to each other. Pointy (sharp actually) to rounded.

[Scrounge]

But why so many different curves to an ogive? I have a dozen .30 cal boolits that all have a different ogive but have the same base and very close weights to each other. Pointy (sharp actually) to rounded.

Everybody and his brother have their own little opinion of what the perfect bullet (or boolit) is, and you know what they say about opinions. Like rectums, everybody's got one, and most of them stink.

[Larry Gibson]

OP didn't ask for definition of olive.

He asked why the ogive is important.

[Scrounge]

OP didn't ask for definition of olive.

He asked why the ogive is important.

Title of the post was " What is an ogive?" Definite question mark there. He did ask WHAT the definition is, AND why it's important. The wiki article a couple of us posted and several of the other comments answer both questions. What and why.

[Larry Gibson]

As I understand it, an Ogive is the slanty portion of the boolit from the thickest part to the tip. (Yes slanty portion is a technical term )
But why is it important? This is eluding me.

Read the message, OP understands the "what". He is asking for the "why"

The wiki site lists several "what" but only lists one "why". There are several "why's". Just trying to help the OP get all the information that is eluding him.

[Traffer]

I have recently made swaging dies for 9MM Parbellum. To my chagrin, when testing the loading with some made up dummy rounds, they stuck in the throat of my pistol. (Don't you just hate it when stuff gets stuck in your throat?)
I finally actually measured the ogive on the things...They looked good but the ogive was too short. So I went and measured out a "2" ogive. The same as the very common round nose Lee 124 gn mold. I also left the "step" in the bullet where the ogive starts. Here is a picture of the difference. The one on the left is the short ogive. Middle is the reworked ogive. The end one is the bullet from the mold.

[GregLaROCHE]

The olgive is important when hunting. It can make the difference if the boolit will quickly mushroom, penetrate deep, if needed or just pass right through leaving minimal damage.

[country gent]

Ogive does affect seating depth as a side effect. Ogive also has a definite effect on feeding and function. The big reason for the ogive is its effect on the bullets Ballistic Coefficient. While not nearly as important on pistol bullets, t makes a big difference on rifle bullets compare the old round nose with the newer vld 6 and 8 ogive bullets its much higher and these bullets shoot much flatter.

These 6 and 8 ogive bullets are also much longer for a given weight meaning a faster twist may be needed for them to stabilize. A good way to see ogive is in the original 6 mm rems they would stabilize the blunt 100 grn round nose some times the spire points not the spitzers or longer pointed bullets. Ogive has a lot of effects and all need to be considered

[1hole]

No one has asked but ogive is pronounced Oh-JIVE. And ogive is the entire portion from full diameter to the meplat (nose).

[Traffer]

No one has asked but ogive is pronounced Oh-JIVE. And ogive is the entire portion from full diameter to the meplat (nose).

Why does that song "Willie and the Hand Jive" always come to mind when I think the word ogive?"
DIG THAT CRAZY OGIVE

[Dapaki]

Everybody and his brother have their own little opinion of what the perfect bullet (or boolit) is, and you know what they say about opinions. Like rectums, everybody's got one, and most of them stink.

Very funny!

I was really teasing a bit and was hoping that Larry would wax on about “tangent” and “secant” bullet shapes.

[Tazlaw]

Thanks guys! You have helped me with more knowledge.

[Bazoo]

The ogive has some to do with bullet stability when transitioning from supersonic to subsonic but not as much as aerodynamics in flight. What does have a major influence in the transition, is if the bullet is bevel base or plain based, with plain being much more stable when breaking through the pressure bow. Whether or not the bullet has driving bands or is smooth sided has a pronounced effect, with bullets featuring driving bands being able to make the transition better. The bands cause turbulance to disperse before it reaches the base.