Ogive Variation?

L

Lynn

Registered User
If you take a box of bullets and measure them with a 22 caliber comparator first then a 6mm comparator second how much variation do you see? In other words if they all measure within 0.001 with the 22 comparator would they all measure within 0.001 with the 6mm comparator as well?
I have read that the ogive is very consistant but I am not finding this when actuially measuring my bullets.
Lynn aka Waterboy
 
Lynn,

This does not answer your question but the first thing that comes to my mind is, how accurate are the tools being used for measuring?

Adrian
 
Lynn,

The 6mm comparator will index closer to the shank/bearing surface of the bullet, which has a very very shallow taper, and the reading will be less accurate. If you take it to the limit at an angle = 0+, then the index point is undefined :)

I try to keep things simple, maybe too simple. At bullet pointing stage, I check overall length on almost every pull, the moment they start to deviate more than ±0.002" I take corrective actions.

If you knew all bullets from a given box came from the same die (Berger, for instance), then overall bullet length is a quick and accurate way to determine bullet consistency, I think.

George
 
Bob Green makes a tool that measures the distance between where a seating stem would contact the ogive, and where it would contact the leade angle of the rifling in the throat. I have one that I am "looking" at various bullets with. So far, the custom short range bullets look pretty good. Mass produced bullets are another story. If you need to get the most from factory bullets, or want to do one more quality control step on custom bullets, you should have one of these tools. Deciding which one to get should be easy. I believe that he is the only one that makes them.:D
 
Lynn...I have several of the Sinclair ogive checking devices, and I found that they tend to "bite" into the bullet ogive when you run the caliper up against the base of the bullet..soo much so that some bullets have to be physically pulled out of the gage...I recommend that you put the gage into a lathe and put a small radius on the edge with some 320-400 grit paper to keep the gage from "biting" the soft gilding copper jacket...It will help..
 
eww

I have a pair of the Davidson comparators 22 and 6 that attach to a vernier caliper. I make 22 and 6 bullets for BR. I use the comparator to record seated bullets ogive after they are seated. This way If I changed to another bullet I could match the seating depth on my die to get the same ogive seated bullet length.

One thing I have found using comparators is you have to be careful in doing your reading more pressure on the comparator will allow the comparator to move farther down on the ogive giving a couple thou smaller reading. I find with Custom bullets that a box of 100 will all measure close to the same maybe .001 or less not enough to make you want to change bullets.

With factory bullets I don't measure and don't care to as there are so many variables in a factory rifle to take away from accuracy the bullet ogive variations if not extreme will not improve or lessen one's shooting.

I don't want to spend the time but just for curiousity sake take 3 boxes of factory bullets in .22 cal. say Sierra, Hornady, and Nosler measure 20 bullets from each box for ogive variations, shoot the same measured bullets from the same factory rifle using the same brass when you change bullets at 100yd and compare the shooting results. See if the bullets with the least variation shot any better than the bullets with the highest variation. Report back.

Stephen Perry
Angeles BR
 
I just sorted 2300 bullets from the same lot# but they are not true custom bullets.The bearing surface length went from a low of 0.379 to a high of 0.385 with most at 0.380, 0.381 and 0.382 I also weight sorted them and had 3 distinct weights with 85% being the same weight.
I took the small quantities or oddballs and planned on using them to test out some 8208 XBR powder in a straight 6BR.I put a comparator onto my caliper to set my seating depth as this barrel really likes 2.510 inches including the comparators length.I was seating the bullets with a Redding competition seater and getting most of the bullets right at 2.510 but I had some way way short and a few way long.
There is about 3/8 of an inch of clearance before a meplat would hit or bottom out on the seating stem and the stem isn't cracked allowing false readings.I have had that happen before so I checked it first.
Measuring from the casehead to the ogive with a single caliper mounted comparator I have up to 0.030 variation from shortest to longest and I don't know how this would be possible unless the ogive was all over the place.
Lynn aka Waterboy
 
Lynn

I do not know it for a fact, but I have always heard that bullets in the "semi custom" category, (Sierra, Hornady, etc), are made from multiple dies, even bullets from the same box could come from different dies.

Perhaps that is where the problem arises

I have taken the time to measure true custom Benchrest Bullets, from the same lot, every way you can amagine, and as skilled as I am at measuring stuff, I can not detect much of any difference in any criticle dimension.........jackie
 
jackie,

There were claims floating round the net a year or three back that Sierra had modified their production of Match Kings so that all projectiles in a box were from the same die. At the time, my long range projectile of choice, the 200 SMK did exhibit a high degree of uniformity when I ran my comparitors over it.

I don't know how it stands now - I've moved on.

John
 
Jackie
I just checked some 103 Clay Spencers loaded in the same seating die and the variation seems to have vanished.

George
I checked the over all length on a handful of bullets and the bullets with a similar length were more consistant than those picked randomly.

Lynn aka Waterboy
 
The tool that I wrote about gives you a chance to see ogive variations without having to seat the bullets. The bullet is inserted till it stops on the "throat" and moves a closely fitted floating "seating stem" that pushes a .0001 dial indicator. The variations that are measured will show up as variations in seating depth relative to the rifling. (as if the seating stem was readjusted to different settings from bullet to bullet with bullets that were truly identical)
 
Boyd
How do I get one of those tools.I am in the process of sorting 2300 bullets and I want them as uniform as possible before tipping them.
Lynn aka Waterboy
 
If we're interested in variation in seating depth, would not the stem of the seating die have to be factored in?

So, would not loaded rounds have to be measured as well?
 
This Subject

has been discussed many times on here. You might be able to find some of them in the archives.

Essentially you have believers and non-believers. Pretty much they way life goes, ain't it?
 
Pete
I don't know how you can have non believers? My loaded rounds should all measure within reason and they don't.How can you not believe that?
Lynn aka Waterboy
 
Boyd
I just read the link you posted and it is 100% spot on with what I am seeing.
Lynn aka Waterboy

SGJennings
My seating stem is a hollow tube so it should contact the bullet well up on the ogive and thus my seating depths should be very similar.When measured they are not real similar they are exactly like what is described in Boyds link.
Lynn aka Waterboy
 
I might have been Bob's first customer for his ogive comparator, as I was sick of waiting for a machinist to finish mine(which was like Bob's). It's a good tool.

I've found occasional bullets that leave the pack in 139Lapuas. Further testing showed that these caused big differences in trimmed meplat diameters.
This, because 'meplat trimmers' are actually 'nose trimmers', which are dependent on assumed ogive consistency.
I can imagine there would be slight seating differences as well.

I'm R&Ding a laser mic for bullet comparison, that will flat out provide every dimension with BC indication next.
 
I've found occasional bullets that leave the pack in 139Lapuas. Further testing showed that these caused big differences in trimmed meplat diameters.
This, because 'meplat trimmers' are actually 'nose trimmers', which are dependent on assumed ogive consistency.

MikeCR
This is exactly what I am seeing.I have been sorting bullets for years but I now plan on tipping them as well.When sorted for bearing surface length the ogive or nose length is still so different bullet to bullet that when meplat trimmed the diameters vary quite a bit.I have been re-measuring them by overall length once the bearing surface length is done and putting them into smaller subgroups.
I am hoping that after meplat trimming the diameters are very similar and I can point them and shoot them in like groups.
The seating depth variation in my opinion is caused by the large fluctuation in ogive/nose length.
Lynn aka Waterboy
 
I'm not being a smart ass, really, I would like to know if anyone who shoots BR at all seriously these days uses Sierra or Hornady or any of the Mass produced bullets in competition. I was told long ago, that the bullets I was using (Sierra MK) and I found to be very good in service rifle matches, were made three at a time from three different dies, and hence not the best for BR.

Now, say what you want about the NRA, but they can sometimes be a wonderful source of information. On one of the American Rifleman TV shows, they took a trip through the Sierra manufacturing facility. They showed Bullets being jacketed and sent down the chute for boxing. There on the screen in close up were three dies stamping out bullets and the bullets all being mixed together bound for the lil green boxes we all know. I do use Sierra MKs for other applications and have checked them closely with my Sinclair hex nut comparator. They do tend to fall into three rough groups as far as base to ogive, not really a lot different, but more than I like to see for BR. It will be interesting to see some match results and equipment lists when the new AR class gets going, though. I do believe Sierra has the most AR shooters presently.
 
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