OGIVE measurement differences

[James 1]

Using .284 nossler accubonds160 gr. I had 2 bullets I would use for testing overall length in my 7mm when developing a new load. I decided to buy a hornady measurement tool that measures to the ogive. Both bullets are 1.403 inches long. But a big difference in base to ogive. Seems too big of an error to me. Any ideas? I dont have anymore of the older ones left. Just the newer ones.

[260 Rem]

Differences could be due to inconsistent bullet placement where the base contacts the caliper blade...either off center or tipped slightly?

[catnthehat]

Originally Posted by James 1

Using .284 nossler accubonds160 gr. I had 2 bullets I would use for testing overall length in my 7mm when developing a new load. I decided to buy a hornady measurement tool that measures to the ogive. Both bullets are 1.403 inches long. But a big difference in base to ogive. Seems too big of an error to me. Any ideas? I dont have anymore of the older ones left. Just the newer ones.

Dud you notice a difference in the accuracy ?
How many thousandths difference?
Digital calibers are notorious for not being super accurate BTW
Cat

[James 1]

I have 2 of the shorter measuring bullets. I also broke out a new box and they are the longer ones. Mitatoyo calipers are extremely accurate and the measurements are repeatable, so no bullets twisting in calipers.
Its definitely different. Especially when loading to 0. 020 off the lands.
No issues with accuracy, but I have allways used COAL, thought I would try to be a little more accurate and try base to ogive.
Maybe I had a bad batch of bullets, who knows?

[catnthehat]

Originally Posted by James 1

Using .284 nossler accubonds160 gr. I had 2 bullets I would use for testing overall length in my 7mm when developing a new load. I decided to buy a hornady measurement tool that measures to the ogive. Both bullets are 1.403 inches long. But a big difference in base to ogive. Seems too big of an error to me. Any ideas? I dont have anymore of the older ones left. Just the newer ones.

Originally Posted by James 1

I have 2 of the shorter measuring bullets. I also broke out a new box and they are the longer ones. Mitatoyo calipers are extremely accurate and the measurements are repeatable, so no bullets twisting in calipers.
Its definitely different. Especially when loading to 0. 020 off the lands.
No issues with accuracy, but I have allways used COAL, thought I would try to be a little more accurate and try base to ogive.
Maybe I had a bad batch of bullets, who knows?

Is the whole box s different length but accurate as far as th. Bullets in the particular box?
Different lot numbers maybe?
What is the difference in the lengths?
Cat

[James 1]

Originally Posted by catnthehat

Is the whole box s different length but accurate as far as th. Bullets in the particular box?
Different lot numbers maybe?
What is the difference in the lengths?
Cat

1. I only have 2 of the shorter bullets left. They are the ones I have allways used to measure COAL in different rifles.
2. Bullets would have been bought at different stores, so I assume different lot numbers
3. All Bullet lengths are all the same 1.403 inches

[Scotty454]

Originally Posted by catnthehat

Dud you notice a difference in the accuracy ?
How many thousandths difference?
Digital calibers are notorious for not being super accurate BTW
Cat

Those Mitutoyos should stay accurate and repeatable to a thousandth or so over their entire life, assuming they're never dropped hard, or smacked into too many things. Mitutoyo is pretty much the standard for quality beam calipers.

That said, you have to know how to use them properly. They do lend themselves to user error, just like any precision measurement tool.

[catnthehat]

That's interesting , same top yo vase length bug different ogive lengths.
Obviously the factory changed someone for whatever reason!
When I was having my Ruger built the gunsmith had mention that one billet company had hsd used fog years had changed their bullet diameter for no sppeteant reason !
Cat

[James 1]

I wish I had more of the older accubonds

[Robmcleod82]

Originally Posted by catnthehat

Dud you notice a difference in the accuracy ?
How many thousandths difference?
Digital calibers are notorious for not being super accurate BTW
Cat

Laughing!!! Funny never have too big a descrepency between a set of mitutoyos or starret and what a micrometer reads. Have a machinist buddy that swears Canadian tire digital calipers are just as accurate. Inaccuracy in measuring tools usually ends up more being to do with the guy operating them not knowing what he is doing.

[catnthehat]

Originally Posted by James 1

I wish I had more of the older accubonds

One way to ensure that when you find a component you like you will have some in the future ?
HOARD!!
Cat

[Robmcleod82]

I found a fair bit of ogive descrepency in some 7mm accubonds and 338 accubonds coming out of the same box so a major difference lot to lot wouldn't surprise me. I would imagine the dies used to make the bullets would be subject to a fair bit of wear.

[urban rednek]

Verify the weight of the bullets; an extra 20 thou. of body length could translate into an extra 5 grains of bullet weight.
Or, if the weights are a uniform 160gr, it is possible that the manufacturer has changed the composition of the alloy. A lighter alloy could explain the extra body length. If this is the case, and you shoot long range, you might want to check with Nosler to verify the SD and BC of these newer bullets.

[Dean2]

What you are finding is pretty common. If you take Hornady .284, 139 grain BTSP from 20 years ago and a box bought today, they both have the same overall length but noticeably different ogive length and shape for that matter. The same is true for their 162 grain Boattail Match bullets. This can be the result of changing the jacket, interior lead or trying to optimise the B.C. of a bullet.

The change can often be enough to cause changes in the way the load groups, requiring a different COAL to compensate. I have never seen the change require a change in the powder or powder charge weight.

[James 1]

Interesting. I never would have thought they would do that. Learn something new everyday.

[Hawkeye]

Could it be as simple as two machines, producing bullets with slightly different ogives, being used together on a production line and bullets from both machines getting packaged into the same box?

[tchardy1972]

What your seeing is the difference in lots. I have seen fairly major differences from all manufacturers including tip shape and oal. For rifles that matter I buy bullets by the 1000.

[Bushrat]

Not unusual at all. If you start measuring bullets over the years, or from lot to lot even sometimes from bullet to bullet in the same box. Dies get changed, dies go out of adjustment, new dies verses old dies on the same production run all these and other reasons will give different sized bullets in the same box. That why many guys who are after the best accuracy they can get don't buy commercial off the shelf bullets. They buy custom made bullets all made off of one die with the same operator pressing each individual bullet so each bullet is as close to each other as possible made with the same lot of jackets and cores.

[catnthehat]

Originally Posted by Robmcleod82

Laughing!!! Funny never have too big a descrepency between a set of mitutoyos or starret and what a micrometer reads. Have a machinist buddy that swears Canadian tire digital calipers are just as accurate. Inaccuracy in measuring tools usually ends up more being to do with the guy operating them not knowing what he is doing.

I fail to see what you find so funny .
That is what I was trying to explain .
The digital readouts vary more than with a standard vernier with slight variances of operator tension .
I wasn't comparing them to a micrometer .
Cat

[Full Curl Earl]

I didn't get that either?

[Robmcleod82]

igital calibers are notorious for not being super accurate BTW
Cat

What you said and what you meant were two very different things I guess. Again digitals are not less accurate then a dial if anything they have a finer resolution.

[Pokey50BMG]

If long range accuracy and precision is your goal, you should always sort bullets by projectile base to ogive. Cartridge Base to Ogive is far more important the Cartridge Overall Length. Rather than go into detail about it's importance here are two articles that explain it better than I can:

Part 1 : http://www.bergerbullets.com/effects...e-cbto-part-1/

Part 2: http://www.bergerbullets.com/effects...e-cbto-part-2/

You can sort your projectiles with your Hornady Comparator or here is a precise and more accurate tool:

http://www.sinclairintl.com/reloadin...prod38769.aspx