Ogive Measuerment???

G

gene10pntr

New member
Once you've found out what the ogive is...is that the measurement you use for you're COAL? I realize you will move it back off the lands for the reading you want to seat at. Will that be the measurement you set you're die at then too?

Thanks!!!
 
Originally Posted By: pahntr760I set all my round on a base to ogive measurement. It is a more consistent spot from which to measure.

Me too.
 
I sue the same bullet I use to measure my ogive distance to set my dies to that length. I then pull that bullet and save it in a bag so I can reset my dies later if I load that same bullet again and change in between. Also by keeping that as my reference bullet I can check for throat erosion or use it to check a similar chambering so that it is always apples to apples.

I also track the various measurements on each bullet. I can literally dry lab a new bullet if I have those numbers to indicate if it will go into the case enough or has a hope in Hades of reaching the lands. I eliminated the new TMK's that way for one of my wildcats.

I have found that PUBLISH bullet lengths are not always correct and going buy the book would be a major mistake on some. I had one that was a 30 caliber that if loaded to book length would fall out of the case literally as it wasn't seated into the mouth period!!

Greg
 
You are correct. But keep in mind every time you switch brands of bullets and the bullets are of the same weight, you will still need to establish a new COAL. The o_give from one manufacturer to the next will not be the same. Some folks are under the impression the a 120gr is a 120gr is a 120gr.
 
Originally Posted By: Mark204You are correct. But keep in mind every time you switch brands of bullets and the bullets are of the same weight, you will still need to establish a new COAL. The o_give from one manufacturer to the next will not be the same. Some folks are under the impression the a 120gr is a 120gr is a 120gr.

Ah were it only so.
crazy.gif
I would have a whole lot less reference bullets in my baggies.

Greg
 
But is your seating stem seating at the ogive? If not, wouldn't inconsistencies from the ogive to the tip cause the ogive seating measurement to vary?
For instance..
When I seat my 68gr hp bullet in my 223 ammo, my seating stem leaves a nice ring around the top of my bullet but no where near the ogive. So if there were inconsistencies in the distance from the ogive and where my seating stem makes contact with the bullet, wouldn't that cause my oal to vary from ogive to base of case similar to coal from tip of bullet?
 
I have found theangularity of the taper from bullet to bullet is pretty constant. I use mostly Redding or Hornady seaters and they come out dead nuts for me. If you are getting denting then you may have an issue as all dents are not created equal in depth. Sometime you need a different stem for the longer target VLD style bullets and the factory helps there. You also may have too much neck tension on the bullet from undesizing the necks resisting seating.

Greg
 
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mark 204 said that ogives vary from manuf.to manuf...not only is that true , bullets will vary w/ same manuf.. lot to lot.. had it happen w/ 85 gr,sgk and i called them and they said that is just the way it is ..make a new dummy load w/ every box
 
Be sure to use a measurement system that does not measure off the tip of the bullet.

Greg's advise is great, save the bullet that you use to measure OAL, keep it in a tiny parts bag in your die box.

You should measure the oal on your barrel on a regular basis, as barrels are finicky on what will shoot bug holes, especially if you are shooting some brand of a Very Low Drag bullet.

Learning to measure the OAL to the .001 is the beginning of serious accuracy shooting.





http://www.midwayusa.com/product/709931/hornady-lock-n-load-bullet-comparator-body

http://www.midwayusa.com/product/727771/hornady-lock-n-load-bullet-comparator-insert-224-diameter

I have been using a method that will repeat to the .001 with some practice. Slit a case neck one time and one time only with a thin Dremel cut off wheel, insert a bullet in the case neck, now chamber the round. At first you may have left the bullet pulled out too far, and the lands will grab the bullet with a result of pulling it out. So, push the bullet further back in the case, start over. It is often helpful to put the rifle in a rifle vise, and insert the cleaning rod in the barrel to begin with to knock the bullet out if/when it gets stuck in the lands.

This process goes quickly, and you should measure each brand of bullet, keep that bullet in a plastic bag in your die box to measure the lands growth.

Benchrest shooters and long range shooters also examine the bullet on live round to see if they have equal lands marks on the bullet for a "jam" length. This Jam length is then adjusted to .000 into the lands or .000 off the lands, but determining the Jam length is critical.

There are several methods used in accurately measuring OAL, you just need to master one of them if you are wanting the best accuracy in your rifle. I do bed the rifle, freefoat the barrel, and adjust trigger before I ever fire a shot.
 
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All great info guys!!! I realize each bullet from different manufacturer is not the same too or a different grain of bullet. So to make sure I'm doing it rite...measure from the bottom of the case to ogive to give me the OAL. Correct? Say the book says it's a 2.260..set the die to measure from the ogive and not the tip of bullet to get that???
 
Yep you have it down. Start yourself a reference list so you can refer to it when you have several bullets to load. Mine is over 100 deep now in combined calibers. Buy the Sinclair tool and you will find it is very fast and easy and pain free to boot.

Greg
 
Originally Posted By: gene10pntrAll great info guys!!! I realize each bullet from different manufacturer is not the same too or a different grain of bullet. So to make sure I'm doing it rite...measure from the bottom of the case to ogive to give me the OAL. Correct? Say the book says it's a 2.260..set the die to measure from the ogive and not the tip of bullet to get that???

Most books I've seen give OAL as base to tip of bullet. Except to know if it will fit a magazine, this number is almost useless. The "OAL" you care about is not really "Overall" at all. But it's the one that matters.
 
The Hornady modified cases are useless in the way they instruct them to be used. Unless you reference the modified case against a once (or twice/thrice) fired case and add or subtract the appropriate headspace length, they're 100% useless - just a shot in the dark. All they really let you do is measure from the chamber shoulder to the lands - there's no guarantee with the bolt open that your headspace length on the modified case is the same as your actual rounds. Used properly, having the shoulder datum to lands datum distance is really valuable, but that's not how hornady's instructions read.

As mentioned, COAL is irrelevant except for magazine allowance and ejection. The bolt face to the shoulder datum line, then to the lands are the two distances you actually need. I set my dies to give me the proper headspace for my chamber, then I do all of my seating with a bullet comparator in my calipers.

The tips just hang in dead air, no reason to measure anything against the tip.
 
Varminterror said:
The Hornady modified cases are useless in the way they instruct them to be used. Unless you reference the modified case against a once (or twice/thrice) fired case and add or subtract the appropriate headspace length, they're 100% useless - just a shot in the dark. All they really let you do is measure from the chamber shoulder to the lands - there's no guarantee with the bolt open that your headspace length on the modified case is the same as your actual rounds. Used properly, having the shoulder datum to lands datum distance is really valuable, but that's not how hornady's instructions read.







I started to dis-agree but after thinking on this, your actually only measuring from the shoulder to the lands. Correct?
Click to expand...
 
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The Hornady cases do fail on the measurements as stated above. The only way around this is to have your personal fired cases fitted by Hornady or drill/tap your own. The later is quite easily done once the tap is obtained.

A far better method is the use of the Sinclair tool for determining distance to lands. A case fired in the chamber and the bullet of choice allow one to get repeatable measurements quickly and accurately at a very low price.

Greg
 
I believe the Hornady tool referenced earlier in the thread was the one which uses a collar of appropriate diameter for caliber and clamps to your caliper to measure base to ogive, not the land distance tool using the modified case. The former is very useful, the latter I've always used other, more accurate methods.
 
Originally Posted By: springerI believe the Hornady tool referenced earlier in the thread was the one which uses a collar of appropriate diameter for caliber and clamps to your caliper to measure base to ogive, not the land distance tool using the modified case. The former is very useful, the latter I've always used other, more accurate methods.

Yep but you have to get that length somewhere. I can also show where the bullet colimator set up is not exactly the bee's knees either because of the design of the opening.

Greg
 
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