Ogive Variation?

[Greg Culpepper]

anybody shoot Sierras seriously?

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.

amamnn,

I bought 3000 of the 107 SMKs to shoot in F-Class and for my step daughters's 600 yd BR shooting to save cost compared to Clinch Rivers for the less demanding applications. Rebecca had to have a vitrectomy in her shooting eye and gave shooting up for awhile. At the last match at Piedmont in 2008 I shot her rifle (newly chambered take off barrel in a no turn neck 6BR for economy an simplicity) with the SMKs and got the HG agg and 2nd place group in LG. In 2009 I shot only three 600 yd matches (all at Piedmont and again with her rifle) and got enough club points for 4th and 11th place in IBS SOY. That last (August) match at Piedmont those Sierras got 1st for HG score, 1st LG group and 1st LG score. As you know, Piedmont is a tough crowd and two weeks later my NC colleagues Sam, Mike and Rodney went to Pierre where they finished 1st, 3rd and 4th at the IBS Nats and Sam of course clinched SOY for the second year in row.

The SMKs 107s will run with the big dogs. The attached photos are the most recent 600 yd and 1000 yd IBS targets I shot with those bullets also with that same rifle. Chris Collins was pulling the target next to mine at Butner and reported the the first three shots on the 1K target made the 1.2" wad in the middle. Bless those fishtailing winds!

These Sierras are the most uniform bullets that I have ever measured (I've measured most) and clearly are not mixed from more than one die. I've shot them measured but unsorted (there is nothing to sort) but more often than not pointed with a Whidden die. I haven't done any comparative testing against other bullets or even tuned this combo. They shot good the first time I tried them and they still do. After 1400 rounds I'm still shooting the exact load that my gunsmith Mark King suggested when he sent the rechambered barrel back to me. It's my first 6BR.

Hope this helps answer your question,

Greg

 

[amamnn]

As has been said time and again-- everyone's experience is different. I have not measured a lot of 107 MKs but I have measured 100's maybe 1000's of 224 and 6mms in lighter weights with the results I noted above, with very few exceptions. Certainly a box could get filled mainly with bullets from one die, though the odds are against it. I can't say for sure that I noticed the measurements falling into roughly 3 groups before or after I was told about and actually saw the three dies working, but I can say that I had cull a lot of MKs before and after.

I'm not sure that my scores really improved by going to a hand swaged bullet, but the time and effort culling is much much less. I don't consider myself to be as picky about base to ogive as other people; I cannot afford to reject half of what I buy, and I still use MKs, just not for short range BR, which is after all, the forum.

 

[Greg Culpepper]

anybody shoot Sierras seriously?

As has been said time and again-- everyone's experience is different.

I thought you were asking for other peoples experience, you know, different than yours. I gave you mine. Or were you just hoping to create an opportunity to disparage mass produced bullets.

I have not measured a lot of 107 MKs but I have measured 100's maybe 1000's of 224 and 6mms in lighter weights with the results I noted above, with very few exceptions. Certainly a box could get filled mainly with bullets from one die, though the odds are against it. I can't say for sure that I noticed the measurements falling into roughly 3 groups before or after I was told about and actually saw the three dies working, but I can say that I had cull a lot of MKs before and after.

10 years ago it was a fact that 6.5 142gr SMKs could be sorted into three distinct groups. Not true anymore. That was then, this is now.

I'm not sure that my scores really improved by going to a hand swaged bullet, but the time and effort culling is much much less. I don't consider myself to be as picky about base to ogive as other people; I cannot afford to reject half of what I buy,

Who can afford to reject half? I can't and I've yet to cull a single 107 SMK. I've found nothing to sort, let alone cull. And I am picky.

and I still use MKs, just not for short range BR, which is after all, the forum.

I thought this was the "Competition Benchrest Only!" forum, not just for short range BR. After all, you posted your question on this thread started by a long range BR competitor about long range competition bullet ogives.

I'm not being a smart ass, really.

Really?

Seriously,
Greg

 

[skeetlee]

What about the new tool from sinclairs. They are about 120 bucks with a dial. Would it be worth the money? I only have one of the hexagon tools from sinclairs and i think it is next to useless. The bullets get stuck and marred up, and i get different reading on the same darn bullet, depending on how much force i apply with my calipers. I try to be carefull and apply the same force but it doesnt work real well. Maybe i need to do the champher (sp) trick? 20 bucks i could have better spent i think. Thanks Lee

 

[amamnn]

Really! Some time ago I was reminded by other members of the site that there were other forums here for things like F-class and 600 and 1000 yard BR shooters to post on and that I should post short range info here and stay off the others with that stuff...........

I would never belittle nor denigrate anyone's personal experiences, BUT a 107 grain bullet used in the other classes is NOT a 68 grain bullet and a base to ogive variation of something like say, .002" may be acceptable to a user of the longer bullet where it would not be to someone using the shorter one. It is a matter of percentage of variation from the mean, not absolutes. This is my experience over 50 years of handloading.

It seems to me that you are comparing apples while I was asking about and relating my experiences with oranges--if this offends you--well I'm not sorry, but I hope you can understand my position a bit better, if not-- you can easily just ignore me or anyone else you care to.

 

[mikecr]

What about the new tool from sinclairs.

Sinclair doesn't have a tool that measures ogive radius variance.
Are you referring to a bearing surface comparator?

 

[Joe Salt]

You're right Pete, somtimes I wonder why I read these postes. Some people just don't get it.

Joe Salt

 

[Greg Culpepper]

Really! Some time ago I was reminded by other members of the site that there were other forums here for things like F-class and 600 and 1000 yard BR shooters to post on and that I should post short range info here and stay off the others with that stuff...........

Well maybe someone will step up and scold Lynn for you about being on the wrong forum.

I would never belittle nor denigrate anyone's personal experiences, BUT a 107 grain bullet used in the other classes is NOT a 68 grain bullet

The discussion was started by a long range competitor and continued on about long range bullet issues

and a base to ogive variation of something like say, .002" may be acceptable to a user of the longer bullet where it would not be to someone using the shorter one.

Long range shooters who sort will sort to the nearest thou. I'm not aware that short range shooters sort bullets at all but rather find what works for them and load them. I suspect short range shooters don't sort because it doesn't matter at short range although it certainly can at long range. Or maybe the blunt short range bullets just pop out of the die more uniformly than VLD types. But Lynn is talking about taking sorting to the next level to include ogive variations, not just bearing surface length. Short range shooters are only recently discussing the utility of weighing powder charges vs dropping to a 2/10ths window. Many long range shooters have been weighing charges to 2/100ths for years because for them it makes a difference. It seems evident that long range accuuracy issues include some things that don't influence short range results

It is a matter of percentage of variation from the mean, not absolutes. This is my experience over 50 years of handloading.

So you've been sorting short range bullets for bearing surface length for 50 years? You are the first person I'm aware of who thinks it might contribute to greater short range accuracy. How's that worked for you?

It seems to me that you are comparing apples while I was asking about and relating my experiences with oranges--

I thought the discussion was about apples--you seem to be the one who introduced the new fruit.

if this offends you--well I'm not sorry, but I hope you can understand my position a bit better, if not-- you can easily just ignore me or anyone else you care to.

? Did you have a question or did you want a platform to take a position?

Greg

 

[criver600]

Ogive variations....

Ogive OAL variations are caused by, short stroking, loose point up die (obvious) and irregular application of lube.

 

[Pete Wass]

As long as

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

there are folks who continue to load bullets ramdomly from the box there will always be less stiff competition.

 

[Joe Salt]

Greg & Pete

You would think if something works at long range, it would help just that little that is needed at short range. Maybe they don't need that little edge. I'm sorry but I believe that ogive to ogive, [Bearing surface] means more than base to ogive! Like you guys said if you get one out of the box that is .030 off from the others your OVAL is not going to be the same. Oh there are a few more secrets than just that. But to me B.S. is the only part that touches the rifling why wouldn't it matter.

 

[Boyd Allen]

There is one little point that I would like to make, and it is not who should be where. As far as I know, there is only one gauge that will show differences in distance from where a seating stem would touch a bullet, to where that same bullet would touch the rifling. Variations in this distance are not the same thing as base to ogive or boat tail to ogive differences, and to my way of thinking should be the best possible predictor of distance to or into the rifling variations in ammunition loaded with a particular batch of bullets. Opinions?

A related question that I would like to hear opinions on is how much variation in loaded rounds' bullets' distance to or into the rifling (or from touch) does it take to show up on paper. Also, are different ogive styles (tangent, secant, VLD, or double radius) more or less tolerant of this sort of loaded round variations. What has been your experience Have you actually measured loaded ammunition for this variance? I have not, but now that I am better equipped for the task, I will. I guess that I have always ASSUMED that all of my custom short range bullets were uniform, within a batch, because they all came from the same point die.

Some time back a gunsmith/shooter of high skill, told me of a new short range Benchrest shooter that was seeing quite a bit of ogive to base of loaded round variation in his ammunition. The smith modified his seating stem so that it bore further down the ogive from where it had, and the variance was significantly reduced. It would seem to me that if all of the bullets were uniform, that this would not have made a difference. I am pretty sure that the shooter was using custom bullets, and that they would have all been from the same point die, but for there to be the sort of problem that he was having, there would have had to have been significant ogive shape variations. Would this have been caused by differences in jacket metallurgy, or possibly variations is press stroke as the bullets were formed? Could differences of lube have contributed? It would seem that these would be questions for the bullet makers among you.

 

[Al Nyhus]

I made up a little gizmo that exactly matches the ogive profile of my point die. Depending on what tool is used to measure base-to-ogive dimension, this gizmo can give a more realistic reference number than a traditional back-to-front measurement.

If you use a Stoney Point style comparator, you can get a more accurate base-to-ogive reference by modifying the inserts i.d. to more closely match the shank diameter of the bullet. A .30 cal. insert for the Stoney Point tool actually measures .296, for example.

With the insert .0005-.0008 under the shank diameter, the only difference I find when checking front-to-back with the gizmo or back-to-front with the modified insert comes from how I hold my tongue when measuring.....

 

[Boyd Allen]

Are you measuring to back of bullet or to back of loaded round?

 

[Al Nyhus]

I guess that I have always ASSUMED that all of my custom short range bullets were uniform, within a batch, because they all came from the same point die.

Hi Boyd. I know you know this, but I'll make an attempt here...which I'll probably regret later. So much for another new years resolution.

Even with different base-to-ogive dimensions, bullets from the same point up die will have the same 'seating depth' when you check from the case head to the ogive of the bullet. The only thing that changes is how much of the shank of the bullet is in the neck.

And this is where things get confusing for people...as this does not always directly relate to what I call the seating stem/lands dimension...ala' what the Bob Green tool measures.

Ducking for cover, here........ -Al

 

[Boyd Allen]

Al,
The example that I gave was one where there was head to ogive variation, so it would seem that what you have said is not always the case. Since I invariably seat bullets so that they are longer than touch, and I have a so called gizzy, made with my reamer, I have always had the ability to measure head to rifling contact point variations, it just didn't occur to me to do so. The next time I make it to the range, you can bet that I will probably be spending more time measuring and recording than actually shooting, but this is what it is going to take to see what is actually gong on. As to the difference between seating stem to rifling contact measurements and the typical ogive to base measurements, I get it. That is why I think that Bob's gauge may be a significant advance. It would seem to me that variations is ogive to base of bullet would be less important, but until recently, that is all we could do, with commercially available tools.

 

[Greg Culpepper]

Greg & Pete

You would think if something works at long range, it would help just that little that is needed at short range. Maybe they don't need that little edge. I'm sorry but I believe that ogive to ogive, [Bearing surface] means more than base to ogive! Like you guys said if you get one out of the box that is .030 off from the others your OVAL is not going to be the same. Oh there are a few more secrets than just that. But to me B.S. is the only part that touches the rifling why wouldn't it matter.

Joe,

I agree with every point you make in this post, particularly to your point that bearing surface consistancy is a very important predictor of flight uniformity.

Greg

 

[Greg Culpepper]

There is one little point that I would like to make, and it is not who should be where. As far as I know, there is only one gauge that will show differences in distance from where a seating stem would touch a bullet, to where that same bullet would touch the rifling. Variations in this distance are not the same thing as base to ogive or boat tail to ogive differences, and to my way of thinking should be the best possible predictor of distance to or into the rifling variations in ammunition loaded with a particular batch of bullets. Opinions?

I agree, unless you go to the considerable additional trouble of measuring twice with two different Stoney Point type inserts as Lynn described earlier.

A related question that I would like to hear opinions on is how much variation in loaded rounds' bullets' distance to or into the rifling (or from touch) does it take to show up on paper. Also, are different ogive styles (tangent, secant, VLD, or double radius) more or less tolerant of this sort of loaded round variations. What has been your experience Have you actually measured loaded ammunition for this variance? I have not, but now that I am better equipped for the task, I will. I guess that I have always ASSUMED that all of my custom short range bullets were uniform, within a batch, because they all came from the same point die.

This is not scientific but just annecdotal observation. I think that when close to the lands that blunter bullets (non VLD) are more tolerant to small variations and show a bigger window on paper or to say it another way are easier to tune than than VLDs. This seems counter-intuitive to me. When seating with a jump, I think the requirement for precision seating is lessened.

Some time back a gunsmith/shooter of high skill, told me of a new short range Benchrest shooter that was seeing quite a bit of ogive to base of loaded round variation in his ammunition. The smith modified his seating stem so that it bore further down the ogive from where it had, and the variance was significantly reduced. It would seem to me that if all of the bullets were uniform, that this would not have made a difference. I am pretty sure that the shooter was using custom bullets, and that they would have all been from the same point die, but for there to be the sort of problem that he was having, there would have had to have been significant ogive shape variations. Would this have been caused by differences in jacket metallurgy, or possibly variations is press stroke as the bullets were formed? Could differences of lube have contributed? It would seem that these would be questions for the bullet makers among you.

I think what we might be seeing is the result of bullets being squeezed slightly by the taper on the seating stem to varying degrees from variations in bullet to neck friction or seating pressure requirement. It seems to me that the smaller the contact ring of the seating stem where it meets the bullet the greater the opportunity for bullet to be deformed by seating pressure. It could be that the variation we see on paper from ammo with differing bullet seating pressure is the result of varying seating depth or BC from squeezed ogives.

(Recent edit)
Boyd, do you think that a seating stem that presses on the bullet very close to the bearing surface would reduce seating depth variation by reducing bullet squeezing as I am speculating?

Greg

 

[Joe Salt]

Greg I've Had VLD's as much as 150 thou. off the lands but I try and keep them all within 1\2 thou. on OVAL. I did this to see how far I could go before it changed the vertical. But I feel you have to be consistent with OVAL. And you will get less variation measuring base to ogive than ogive to ogive. that is why people are see the difference in there seating.

Joe Salt

 

[Nader]

There is one little point that I would like to make, and it is not who should be where. As far as I know, there is only one gauge that will show differences in distance from where a seating stem would touch a bullet, to where that same bullet would touch the rifling. Variations in this distance are not the same thing as base to ogive or boat tail to ogive differences, and to my way of thinking should be the best possible predictor of distance to or into the rifling variations in ammunition loaded with a particular batch of bullets. Opinions?

A related question that I would like to hear opinions on is how much variation in loaded rounds' bullets' distance to or into the rifling (or from touch) does it take to show up on paper. Also, are different ogive styles (tangent, secant, VLD, or double radius) more or less tolerant of this sort of loaded round variations. What has been your experience Have you actually measured loaded ammunition for this variance? I have not, but now that I am better equipped for the task, I will. I guess that I have always ASSUMED that all of my custom short range bullets were uniform, within a batch, because they all came from the same point die.

Some time back a gunsmith/shooter of high skill, told me of a new short range Benchrest shooter that was seeing quite a bit of ogive to base of loaded round variation in his ammunition. The smith modified his seating stem so that it bore further down the ogive from where it had, and the variance was significantly reduced. It would seem to me that if all of the bullets were uniform, that this would not have made a difference. I am pretty sure that the shooter was using custom bullets, and that they would have all been from the same point die, but for there to be the sort of problem that he was having, there would have had to have been significant ogive shape variations. Would this have been caused by differences in jacket metallurgy, or possibly variations is press stroke as the bullets were formed? Could differences of lube have contributed? It would seem that these would be questions for the bullet makers among you.

Boyd and others,
I am kind of reluctant to jump in here because I am not in any sort of authoritive position.,nor do I understand the science end of things,nor do I wish to have the "flesh ripped from my bones" by the current flock of non-appreciative BR Central buzzards that have nothing to offer but criticism.
However, in my bullet making infancy,some things have come to light that I never understood before when I was just a shooter( and barely understand now).Anyway, here are my observations for the moment:
Seating stems push on the bullet from a place well above where the ogive contacts the rifling. I have a gizmo(chamber gauge stub that mounts on my "el cheapo"calipers) that pretty accurately measures base of bullet or base of loaded cartridge to the portion of the ogive that actually contacts the rifling in my chamber.. I can also measure a .825 long jacket on a standard caliper, Doing this on 100 jackets, an .825 jacket is boringly .825 long( yeah,J4 !)Now lets core seat some jackets,One with a 65 gr combined weight and one with a 68gr( different punch diameters and die settings of course),the jackets change length a little but remain consistant. Now over to the point up die we go.Same setting, same jacket different weights.The bullets come out of the point up die with the same overall length but with two different ogive readings. The heavier bullet with the longer ogive reading. OK, so take three .825 jackets and three identical weight/volume slugs,and adjust the core seater die up and down a smidge(a freekin smidge)and run these three same weight/length CSJ's in the point die and guess what? three different base to ogive measurements that correspond to heavier (longer)CS pressure or lighter( shorter) CS pressure. OK, so with the most stringent human efforts possible,one is still gonna get a slightly heavier/lighter core jacket combo come down the line and that is where the bullet makers "feel" is gonna notice the difference in CSpressure and hit the brakes and throw that bullet into the "cull pile". Doing that, all of the bullets in that run will have the same base to ogive measurements. Don't do that, or let Sierras machine completely ignore any variances and you will get different base to ogive measurements in your box of bullets.
Now how does this apply to paper? If you tune your rifle on a razors edge and it will only shoot one seating depth and one powder charge and then you throw some not really shure about consistancy bullets in it, your "tune " is going to be easily compromised. If you tune your rifle with a broader seating depth window, then the broader tune will suck up the variation. That is why hard to tune high ogive and VLD's frequently respond to jump tunes. The jump space sucks up the variation ( it should be obvious by now that I'm no scientist)easy to tune low ogive bullets that will shoot from .005 off jam to .015 off jam and do it with three diffrent "numbers" of powder will also suck up the variation.
bullet diameter must also be held consistant to get best performance( in the critical core seating pressure adjustments) So you see, there is a lot more to bullet consistancy and rifle tune than previously meets the eye.
Joel