Cartridge "Ogive length"?

I'm not sure what the correct term is but base to ogive length on a loaded cartridge. I was going through my notes and I noticed something that got me thinking. The ogive length to lands for a cartridge was different from one bullet to another. Shouldn't they be the same? I rechecked the longer cartridge and the measurement was still the same. Letting the lands push bullet into finger tight case mouth. There is a .050" difference?

If these are from the same manufacture then I have no idea they would be different, unless they are a different style. If they are of different manufacture then it’s because each manufacture makes them wth a different taper. I am assuming that all are the same weight . This is one. the reasons that all bullets do not have the same point of impact

They are completely different bullets and different weights. I'm guessing because the ogives have different radius and or designs...

Yes sir you have got it figured out. Even if they look the same they might not be.

you guys have it figured out , it's because of the bullet profile . the hole size on the tool is not caliber size , or the bullet would fall through . so you are measuring from wherever the tool seats on the bullet . a 30 cal bullet is roughly .308 " . the hole in the 30 cal tool will most likely measure somewhere in the .280" - .290" .

edit to add ;
the same profile bullet in different weights will measure the same . the extra bullet length will be inside the case .

Bryan Litz refers to the measurement as Cartridge Base to Ogive (CBTO).

I haven’t noticed a huge difference between bullets, but 0.05 would be possible based on different bullet shapes.


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Ogives vary a lot from bullet to bullet.They can even vary from bullet lot to bullet lot.I check that everytime I start a new box.So it's good to keep good notes on your rifles and how far off the lands a particular bullet shoots well in that rifle.This is very important too if your seating a bullet really close to the lands.A change in the same design bullet could put you into the lands.

Just for clarity:
Ogive: (o-jive) the curved portion of the bullet from the bearing surface to the meplat (see attached).
Meplat: (meh-pla) French for FLAT. The tip of the bullet.
COL: Cartridge Overall Length—distance from case head to meplat.
Unless the bullets are EXACTLY the same (and that includes coming out of the SAME swaging die), the distance from lede/rifling to the point on the ogive where the bullet would contact the lede/rifling will vary.
If using bullets from different manufacturers, there is no hope for the distance to be exactly the same except by pure happenstance.

Ogive is one of those things I have never paid attention to other than I knew that it existed, and that it could have an impact on accuracy in my rifles. I do not have any special chambers, nor calibers. If for some reason I switch bullets, I always start my loads as long as the magazine will allow, then work back. I cannot tell you how far off the lands that is, because it is irrelevant unless you have a very long chamber, a single shot, or you choose to single load your rifle. Just my .02

This is the method I usually use.Just remember to make the case neck tight enough that you can barely insert the bullet and go back through the steps several times to make sure the measurement stays the same.Then you can make you a unprimed dummy round with a sized case and that bullet to make sure it will chamber at the max length.A bullet comparater is a better method of measurement to use once you find your max overall length.Measuring off the bullet tip can vary much more than measuring off the ogive. Write those measurements down.Then from there you can back down.I usually start at .030 off the lands.From what I've read,there is usually two nodes a bullet will shoot good.One is up close and one is farther out.Each one is supposed to have around a .040 range that your bullet will shoot good in that gap. https://www.nosler.com/blog/news-and-ar ... r-your-gun

Elkman":2ngydzat said:

If for some reason I switch bullets, I always start my loads as long as the magazine will allow, then work back. I cannot tell you how far off the lands that is, because it is irrelevant unless you have a very long chamber, a single shot, or you choose to single load your rifle. Just my .02

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I do the same as Elkman other than I do measure my loaded rounds base of shell to the ogive so I know what the bullet seating depth is for an accurate load and can repeat it. Like others have noted the ogive is not in the exact same location even with in a single box of bullets.

OU812":3f68djwa said:

Elkman":3f68djwa said:

If for some reason I switch bullets, I always start my loads as long as the magazine will allow, then work back. I cannot tell you how far off the lands that is, because it is irrelevant unless you have a very long chamber, a single shot, or you choose to single load your rifle. Just my .02

Click to expand...

I do the same as Elkman other than I do measure my loaded rounds base of shell to the ogive so I know what the bullet seating depth is for an accurate load and can repeat it. Like others have noted the ogive is not in the exact same location even with in a single box of bullets.

Click to expand...

That works sometimes,but sometimes you have long mag boxes like Remington long actions and you hit the lands way before you reach your end of the mag box.I have some rifles with short mag boxes and I cannot reach the lands,so I too start at full mag length and work back.

TXbaldhunter":1hu0mpu2 said:

OU812":1hu0mpu2 said:

Elkman":1hu0mpu2 said:

If for some reason I switch bullets, I always start my loads as long as the magazine will allow, then work back. I cannot tell you how far off the lands that is, because it is irrelevant unless you have a very long chamber, a single shot, or you choose to single load your rifle. Just my .02

Click to expand...

I do the same as Elkman other than I do measure my loaded rounds base of shell to the ogive so I know what the bullet seating depth is for an accurate load and can repeat it. Like others have noted the ogive is not in the exact same location even with in a single box of bullets.

Click to expand...

That works sometimes,but sometimes you have long mag boxes like Remington long actions and you hit the lands way before you reach your end of the mag box.I have some rifles with short mag boxes and I cannot reach the lands,so I too start at full mag length and work back.

Click to expand...

I agree with the chance the mag box can be longer than the distance to the lands but I've never encountered it with any of my Remingtons.

Well put txbaldhunter, one other thing is that over time this measurement will grow as the throat eroads more so with something like a 25-06 than a 308. They will both do it but the 25 will do it faster. The magazine box on my 700 measures over 3.600, the 110gr accubonds hit the lands in my barrel at 3.235 Col. Right now it shoots best at a COL 3.175.


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