OAL - Ogive vs OAL

[Tomcat]

When you measure Over All Length do you measure from:
The base of the bullet to the tip (meplat)
or
from the base of the bullet to the Ogive?

It seems to me that the length of a bullet from base to tip is kinda irrelevant. The measurement from the base to Ogive is meaningful because thats where it first contacts the lands.

What say you?

 

[fusiachi]

Re: OAL - Ogive vs OAL

OAL is to the tip, and is relevant to the both dimensions of your magazine and to the effect that seating depth has on pressure.

 

[Nefariousd]

Re: OAL - Ogive vs OAL

Depends,

For AR stuff, base to tip to make sure it fits the magazine.

For Bolt guns base to Ogive.

I differentiate on the labels by writing OAL for the tips and COAL for the Ogive and all of my comparator derived numbers are listed with the additional inch for the comparator. i.e one of my 308's likes the 175 Nosler CC's at 3.220 on the comparator

 

[Fuzzball]

Re: OAL - Ogive vs OAL

"The measurement from the base to Ogive is meaningful because thats where it first contacts the lands."

You are correct. In the sense you mean it, where the tip (meplat) of a bullet hangs in space is irrelivant to anything ballistic.

 

[Tomcat]

Re: OAL - Ogive vs OAL

Guys, Thanks for the insights - I am just getting started reloading and discovering these things.

It seems to me for for 223 reloading is more geared toward reliability - first that the cartridge will fit in the magazines.
For 308, it more to customize the round to the chamber, a with consideration of jump, all while ensuring the cartridge will fit in the mag.

 

[Clark]

Re: OAL - Ogive vs OAL

I used to record my load data with ogive lengths, using a Sinclair Hex Style Bullet Comparator.

That makes sense if one loads .010" off the lands, of something like that.

But I mostly measure where the bullet first touches the lands, measure where the bullet first gets stuck in the lands, and load half way in between. That does not take a great deal of precision.

Half the time I can't reach the lands with the bullet, and if I want to fit in the magazine, I am stuck loading per the max length.


30-06 length cartridges, like 7mmRemMag, are 3.34" max, and often have magazine problems if over that length.
308 length cartridges, like 260Rem, are 2.81", and also have to fit in a magazine.
223 is 2.25" max length, and often have trouble fitting in an AR15 magazine if longer than that.

What does it all mean?
So now I just measure OAL.