Ogive Variation?

SGJennings said:
Al,
Is the geometry such that any one of those four would have seated bullets to a consistent depth? Greg J.
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Greg, all four will seat bullets to a consistent depth.... when measured against itself.

For example, the seating stem I use on my Panda's chamber measures 1.710 overall length. This stem contacts the bullet at the .207 point.

If I take one of the other seating stems and simply adjust it to 1.710, well.......;)
 
I have a question:

What is the position on a bullet called where a seating stem touches it. I assumed the Ogive (curve) extended from the body of a bullet all the way up to the tip. perhaps it's a termanology issue here.
 
Pete Wass said:
What is the position on a bullet called where a seating stem touches it. I assumed the Ogive (curve) extended from the body of a bullet all the way up to the tip. perhaps it's a termanology issue here.
Click to expand...

Pete, I believe your understanding of what the 'ogive' is...the entire curved area foward of the major shank diameter...is probably the most accepted and commonly used.

I probably should have been a little more clear on that in my post and referenced it as the 'ogive origination point' or something like that. I'll go back and reword that.

Thanks! :) -Al
 
Measuring bullets for ogive variation essentially amounts to
using a gage or jig that meets a datum line on the ogive. This really
is based on diameter and measures to base or point. Anything that
changes the diameter,reads as more or less in length. Now if a bullet was fatter in diameter, but shorter in length, it could conceivable read the same.
Measuring loaded rounds from head to bullet point is futile as burs on the points and growth in the die don't relate to changes in lands contact.
Bullet pointing dies don't change enough that we can measure to a datum line on a finished bullet. There are however things that cause bullets to be
different from the same die. Any adjustments in the die are of course
reason to stamp different lot numbers on boxes. Changing a BT punch
because of a crack or chip is no different. Beyond that Bullet lube is
critical.It can make a bullet undersize and even longer. By making the bullet
smaller, it reads in an ogive checker as short to the base. There is also
a great possibility that an out of round ogive checker will allow different
readings when a bullet is checked maybe 90 degrees from the intial
measurement. I once had a die that was out of round and the die maker
replaced it no questions. I opened a new box of bullets that arrived
this morning and measured one for diameter. Being 6.5, I wondered
whether they would be more .264 or .263. With no apparent damage
it was .001 out of round. Going thru the box, it was alone as the others were
fine. Some 308 bullets I had were all marked Oct 13 and I assumed them
to be one lot. I still think they were, but some were .035 longer to the base
from a point on the ogive, a few others were .013 longer but the points were
all completely formed. Apparently some left over from a different run made
it into my oct 13 batch.
 
Bob,
There is a checker that does it differently than either of the methods you described. It measures from the diameter that the seating stem touches (actually somewhere in that area, since they vary) to where the rifling would touch. To do this with the usual tools you would have to have inserts of both diameters and measure each bullet with both and then subtract, for each bullet. You might ask what the utility of the information gathered might be. I would suggest that you read this.

http://greensrifles.com/New_Products.html

As to whether there is the same issue with custom, short range Benchrest bullets, I don't yet know....still working on that one.
 
can you explain why on some bullets there is a difference in length between where the bullet touches the lands and where the seating stem touches the bullet? It is this difference that causes the problem for me.

This is exactly my original question.
Waterboy aka Lynn
 
Lynn,
I thought we spent the last three days doing exactly that? Sometimes it's just not worth the effort,because some people "just don't get it".We'll give you a D+ for being able to turn on the computer.
Joel
 
It may be that the why is less important than being aware that the problem exists, and having a way to "see" the variance, so that sorting can be done, ( where the magnatude is significant), to increase the uniformity of bullets' postions, relative to the rifling, in chambered ammunition. Pant pant...damn, that sentence is way too long.:D
 
Joel
I did appreciate your explanation on how to make bullets and what causes certain problems.
I have been on this forum for 10 years and have read around 34539 posts +-3 about the ogive being the most consistant part of a bullet.
When I sorted 2300 bullets the bearing surface length was 0.379 to 0.385 for all 2300 bullets.
When I then seated 40 bullets for testing I had a larger variation on that group of 40 bullets than I had on the 2300 and the bearing surface has never been known as the most consistant part of the bullet.
I do appreciate your answer to my question I am just having a little trouble finding it and apperantly so is Pete as I cut copied and pasted my post from his.
Lynn aka Waterboy
 
This has been my question as well

Lynn said:
can you explain why on some bullets there is a difference in length between where the bullet touches the lands and where the seating stem touches the bullet? It is this difference that causes the problem for me.

This is exactly my original question.
Waterboy aka Lynn
Click to expand...



Over the past two or three years I have asked this question and to date the best explanation I have seen Bob kingsbury just stated above I think. If the O.D.of the bullet where it will touch the lands changes then the length of the ogive will change.

Perhaps it's more about the cores than anything else. Perhaps more needs to be done to insure cores are more exact, one to another. I have seen this problem blamed on everything in the process and more often than the lube but mebby the lube ain;t it!
 
Pete Wass said:
If the O.D.of the bullet where it will touch the lands changes then the length of the ogive will change.
Click to expand...

Pete, if you're comparing two identical bullets...and the only difference is that one bullet measures .3080 on the shank and the other measures .3084... where the lands touch the bullets will be different. The 'touch point' will be further rearward on the .3080 than the .3084.

Other differences in the 'touch point' come from ogives of different numerical value, i.e.: 7 versus 10, and the angle of the throat.

Depending on the combination, there may or may not be a signifcant difference in the 'touch point'. Using the above .3080 and .3084 bullet examples, using those two 7 ogive bullets into an abrupt throat angle will not change the 'touch point' as dramatically as will the same two bullet diameters....in a 10 ogive profile..... into a more gradual throat angle.

It's not hard to see why some combos exhibit a widely varying difference in the 'touch point' when compared to others combos of 'seemingly' similar components. As two angled surfaces interface, things can get hinky pretty quickly.

I know this is all pretty basic stuff, but maybe it's not a bad idea to touch on it........
 
Al Nyhus said:
Greg, all four will seat bullets to a consistent depth.... when measured against itself.

For example, the seating stem I use on my Panda's chamber measures 1.710 overall length. This stem contacts the bullet at the .207 point.

If I take one of the other seating stems and simply adjust it to 1.710, well.......;)
Click to expand...

Thank you, Al. That's what I was interested in.

Geez, I'm starting to feel deprived that I only have one seating stem....
 
I think what Bob K said, and I could be wrong

Al Nyhus said:
Pete, if you're comparing two identical bullets...and the only difference is that one bullet measures .3080 on the shank and the other measures .3084... where the lands touch the bullets will be different. The 'touch point' will be further rearward on the .3080 than the .3084.

Other differences in the 'touch point' come from ogives of different numerical value, i.e.: 7 versus 10, and the angle of the throat.

Depending on the combination, there may or may not be a signifcant difference in the 'touch point'. Using the above .3080 and .3084 bullet examples, using those two 7 ogive bullets into an abrupt throat angle will not change the 'touch point' as dramatically as will the same two bullet diameters....in a 10 ogive profile..... into a more gradual throat angle.

It's not hard to see why some combos exhibit a widely varying difference in the 'touch point' when compared to others combos of 'seemingly' similar components. As two angled surfaces interface, things can get hinky pretty quickly.

I know this is all pretty basic stuff, but maybe it's not a bad idea to touch on it........
Click to expand...

was if one bullet ,let's say slightly up the ogive measured.300 and another .298 then one bullet would have a longer ogive length than the other. If this be so, this explains why there are differences in the OAL's of loaded rounds with bullets loaded at random out of the box without being sorted by ogive length. I also find it interesting that, from my experirnce, variations in ogive length can be detected when measuring the bullets from the base of the bullet to the beginning of the ogive just above the body. I know it may not make sense but it be the truth.
 
For those shooters that do more than buy bullets and just scoop 'em out of the box and shoot 'em:

- Do you seperate them into 'lots'?
- Do you shoot and quantify each lot?
- How many do you buy to assure a large enough 'lot' to compete with?
- What percentage of the bullets you buy do you deem unusable?

Feel free to add any other items you feel are important to your bullet selection process.

Thanks! :) -Al
 
Pete Wass

I have written some clarifications, in reply and my computer eats
it before complete. In short, ogive to base will show many variations.
Measuring ogives, which really never change from a given die are
subject to the indirect measurement process we use. Much like the neck turner that heats up, the little comparitor on our calipers can go from
60 to 98.6 in minutes and contacts the ogive at a different point.
Yes, when measuring on a taper or curve, it could change .
 
Al Nyhus said:
- Do you seperate them into 'lots'?
- Do you shoot and quantify each lot?
- How many do you buy to assure a large enough 'lot' to compete with?
- What percentage of the bullets you buy do you deem unusable?
Click to expand...

Al
I bought 23 boxes of bullets from the same lot# as that is all the supplier had in his largest lot of like bullets.I put them all into a large bowl and seperated them by bearing surface length.This gave me 0.379 o.380 0.381 0.382 0.383 0.384 and 0.385 lengths with most being 0.380 0.383 and 0.384 inches long.
As one box would become full I would close it and stack another box on top of it.
I then trimmed the meplats on the 3 largest groups of bullets and measured the boattail length and ogive length.The boattails were decent with 3 main groups but the ogives required 13 new sub-groups.
I then weighed them all to 0.1 grain.
I then measured there overall length to 0.001 and pointed up 84 bullets from the same box.At the range I shot 9 groups of 5 shots each and the results were so bad I posted here asking about ogive variations as it was the biggest variable I witnessed.
Today I shot a match using Copperhead bullets from Australia straight out of the box and on the bad relay I still managed 3rd in lightgun and 3rd in heavygun and no there were not just 3 shooters at ther match.
I need 5 identical bullets for each lightgun target and 10 identical bullets for each heavygun target so 230 different groupings would be fine.


Bob
"In short, ogive to base will show many variations.
Measuring ogives, which really never change from a given die are
subject to the indirect measurement process we use. Much like the neck turner that heats up, the little comparitor on our calipers can go from
60 to 98.6 in minutes and contacts the ogive at a different point.
Yes, when measuring on a taper or curve, it could change."

I don't really agree with this statement because my measurements are repeatable day after day no matter the order in which I take them.

Waterboy aka Lynn
 
What I have done since sorting

Al Nyhus said:
For those shooters that do more than buy bullets and just scoop 'em out of the box and shoot 'em:

- Do you seperate them into 'lots'?
- Do you shoot and quantify each lot?
- How many do you buy to assure a large enough 'lot' to compete with?
- What percentage of the bullets you buy do you deem unusable?

Feel free to add any other items you feel are important to your bullet selection process.

Thanks! :) -Al
Click to expand...



is to segregate the bullets in each lot I have sorted by increments of .001. When I find some which are, say .006 off I only use them for foulers, etc.

I only sort because it is easier for me to load and maintain consistent OALs. I find the OAL I want with say a group of bullets that are .003 from whatever size I used as my zero and then when I am out of those I can simply turn my Micrometer stem to the next size and keep on loading rounds with correct OAL's. I find when I try to load using bullets I pick at random out of the box they came in I have to adjust their OAl, measured at where the bullet will touch the ogive or darn close to it. I keep a bullet puller in my turret for this purpose.

I have not found any difference in the way the bullets of any length shoot as long as I move my stem to compensate for the length difference. USUALLY though, regardless of who made them, there will be those few that measure so far out that it is just too much work to use them so they go into the loaded rounds boxes first and get shot up sighting in or fouling the barrel.

I use mostly custom made bullets but I have won a number of matches while using 125g TNT's. If Speer made 115g bullets A LA Berger I would probably use a lot more of them.
 
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