- Thread starter weberj62
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Re: help with ogive and coal
The differance can be simple if you don't over think it.
ovearll length is measured from the base of the caseing to the tip of the round. (cartridge over all length)
since machineing tolarance varie, hence the differance in height of the actual projectiles.
Ogive measurement is taken with a bullet comparator
http://www.sinclairintl.com/.aspx/pid=34262/Product/Sinclair_Hex_Style_Bullet_Comparators
which measures the ogive of the round, normally the curvature of the projectile right before the tip.
the measurement is taken from the base of the cartridge to the ogive, which can give you a more consitant reading.
Memo
The differance can be simple if you don't over think it.
ovearll length is measured from the base of the caseing to the tip of the round. (cartridge over all length)
since machineing tolarance varie, hence the differance in height of the actual projectiles.
Ogive measurement is taken with a bullet comparator
http://www.sinclairintl.com/.aspx/pid=34262/Product/Sinclair_Hex_Style_Bullet_Comparators
which measures the ogive of the round, normally the curvature of the projectile right before the tip.
the measurement is taken from the base of the cartridge to the ogive, which can give you a more consitant reading.
Memo
Re: help with ogive and coal
Think of it this easy and simple way.
You can measure a loaded round from the bottom of the case to the tip of the projectile. This is a total length. This is also called measuring to the meplat.
You could also measure the distance from the bottom of the case to the area of the projectile that is actually the width of its caliber... for example when the tip of a projectile forms .308 diameter, ie the max diameter of the projectile. This is called measuring from the ogive.
The reason people measure from the ogive is because it represents the area of the bullet that contacts the rifling in the barrel. It is also the more consistent measurement of the two.
Bullet meplats are rarely consistent in size and length, hence why measurements from the ogive are considered better.
Think of it this easy and simple way.
You can measure a loaded round from the bottom of the case to the tip of the projectile. This is a total length. This is also called measuring to the meplat.
You could also measure the distance from the bottom of the case to the area of the projectile that is actually the width of its caliber... for example when the tip of a projectile forms .308 diameter, ie the max diameter of the projectile. This is called measuring from the ogive.
The reason people measure from the ogive is because it represents the area of the bullet that contacts the rifling in the barrel. It is also the more consistent measurement of the two.
Bullet meplats are rarely consistent in size and length, hence why measurements from the ogive are considered better.
Re: help with ogive and coal
I also have some confusion on this.
If I measure the chamber to the lands with say a berger bullet, check length with a bullet comparator, then want to use an amax, do I have to measure the chamber again with the amax, or can I use the length found with the comparator?
I also have some confusion on this.
If I measure the chamber to the lands with say a berger bullet, check length with a bullet comparator, then want to use an amax, do I have to measure the chamber again with the amax, or can I use the length found with the comparator?
Re: help with ogive and coal
Every change in bullet: weight, type, and manufacture needs to be checked for length to the lands....i.e. the base to the ogive length may change. and different bullets like different COAL's (one type may like to be jammed into the lands, yet another type may like to "jump the lands" by 0.080inch).
Every change in bullet: weight, type, and manufacture needs to be checked for length to the lands....i.e. the base to the ogive length may change. and different bullets like different COAL's (one type may like to be jammed into the lands, yet another type may like to "jump the lands" by 0.080inch).
Re: help with ogive and coal
The ogive (OH jive) is the entire part from the tip to full body diameter.
For OAL, no rifle knows or cares where the tip (meplat) hangs in the air, what does matter is the jump from seated depth to rifling contact. But, for most rifles, even that depth isn't a specific amount +/- zip.nothing, it's commonly a range as wide as 10-15 thou. So "precison" seating depth is quite helpful but it need not be as precise as some seem to believe. In fact, no matter how precisely consistant we may seat, if we don't seat in the right range our accuracy will simply be consistantly poor while a seating change of maybe 25 thou could make the same load a tack driver.
You must have a "bullet comparitor" tool to seat at a specific ogive point but, truth is, most bullets are sufficently consistant to allow us to use OAL as a "good enough" seating depth, certainly so for factory barrels and chambers.
Understanding it all is nice but what you really need for better groups is to find the best average seating range for your rifle and strive to load in the middle of it so small variations won't matter.
The ogive (OH jive) is the entire part from the tip to full body diameter.
For OAL, no rifle knows or cares where the tip (meplat) hangs in the air, what does matter is the jump from seated depth to rifling contact. But, for most rifles, even that depth isn't a specific amount +/- zip.nothing, it's commonly a range as wide as 10-15 thou. So "precison" seating depth is quite helpful but it need not be as precise as some seem to believe. In fact, no matter how precisely consistant we may seat, if we don't seat in the right range our accuracy will simply be consistantly poor while a seating change of maybe 25 thou could make the same load a tack driver.
You must have a "bullet comparitor" tool to seat at a specific ogive point but, truth is, most bullets are sufficently consistant to allow us to use OAL as a "good enough" seating depth, certainly so for factory barrels and chambers.
Understanding it all is nice but what you really need for better groups is to find the best average seating range for your rifle and strive to load in the middle of it so small variations won't matter.
Re: help with ogive and coal
so i think i understand. so i need two things 1 the device that goes on my cal to touch the bullet in the right area(bullet comparator). 2nd a way to measure the head space to the lands so i can no the chambers c.o.a.l. if this is not right please let me know thanks.
so i think i understand. so i need two things 1 the device that goes on my cal to touch the bullet in the right area(bullet comparator). 2nd a way to measure the head space to the lands so i can no the chambers c.o.a.l. if this is not right please let me know thanks.
Re: help with ogive and coal
Deputy,
Get yourself the following tools.
- Hornady Lock N Load OAL Measurement Tool
- Hornady Modified case for OAL tool, specific to your case of interest
This will allow you to measure OAL with relative ease. Also make sure you have a digital caliper to do all of this with.
To measure bullets at their ogive shoulder get yourself the following
- Hornady lock N load comparitor body
- Hornady comparitor body insert for your caliber (.308?)
Deputy,
Get yourself the following tools.
- Hornady Lock N Load OAL Measurement Tool
- Hornady Modified case for OAL tool, specific to your case of interest
This will allow you to measure OAL with relative ease. Also make sure you have a digital caliper to do all of this with.
To measure bullets at their ogive shoulder get yourself the following
- Hornady lock N load comparitor body
- Hornady comparitor body insert for your caliber (.308?)
