Ogive Bullet Measurements ?

J

Jim D

Member
First I sorted 100 bullets by their ogive. about half were real close.

I then began seating these into charged casings.

I proceeded to measure the ogive again including the case, now I had variation in the ogive again.

The distance between the tip, and the ogive was the culprit.

I have'nt fired any of these, but I fear the varied distance from the lands will give me varied results.

Does anyone make a seating die that contacts the bullet at say the ogive, and not just the vary tip of the bullet ?

I'm just trying get a grip on some variables !

Thanks for any and all imput !

Jim
 
Jim

I thought all bullet seaters used a stem that registered on the ogive, and not the tip.

What seater are you using??..

You are correct. Achieving a consistant seating depth is very criticle in solving the accuracy equation........jackie
 
The stems on my Redding competition seating dies contact the bullets well forward of the ogive.
 
Jim,

Where the plunger strikes the bullet ogive is problimatic.

Have it too close to the junction of the ogive & the parallel case body & the stem will be likely to expand which could cause damage to the seater. This happened to me using a Redding Competition seater with 200-220 grain .308 projectiles - the stresses were just too much for the steel in the plunger. Remember that the closer the body junction the plunger hits, the less meat you have in the plunger, as it's a tad less than projectile diameter.

If it strikes too close to the tip where there isn't any lead, then it could crush the jacket & give irregular registrations. Don't confuse that issue with a badly formed plunger cone which cuts a ring on the projectile tip - they just need to have the edge of the cone broken with some form of lapping etc.

If the plunger isn't properly relieved for the tip of VLD projectiles, then who knows what result you'll get when the plunger presses on the tiny meplat. My .308 Forster needed the centre of the plunger cone recess relieved (I ran in a 5/16" drill, if I recall) when I started to use Berger 210 grain VLDs because they were too long for the original taper of the plunger recess.

Sorry, I haven't used standard seaters foe quite a while & I don't know how they're built these days but I'd reckon they might need a clearance hole drilled like my Forster.

John
 
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Ah ! There in lies my problem !
I have seating dies from RCBS, and a Redding competition seater, and both have a small stem, that just fits the bullet close to the tip.

Who makes a seater that touches the bullet close to the ogive ?

Again thanks !!

Jim
 
Jim,

I would have thought that with standard projectiles, the Redding at least would give you acceptable results. I use mine on light .30 projectiles & the Forster, which has a tad easier tolerances, on the long heavy ones.

However, I've read your first post a couple of times since & wonder how you're measuring your ogive. Are you using a Stoney Point or similar device to measure from a notional ogive/body junction to the base of the projectile, or are you measuring in some other way? It was the reference to the bullet point that had me thinking.

Additionally, is your seating die properly locked into your press. If I don't set up my seaters with the sliding, springloaded bodies correctly, they have a tendency to unscrew as you continue to seat.

With the Redding, you will know if you are putting too much strain on it when you strip it for cleaning, because the seating plunger scores the bore of the cylinder when it expland, such is the close fit of the parts.

John
 
Hi John

I have a Stoney Point Comparator.

Everything was snug, and the COL was consistant

Just the measurement , from the base of the case to the ogive on the seated bullet was inconsistant.

This is a 223, with 50gr. bullets.

Jim
 
Are your primers fully seated?
The Stoney Point in my limited experiance usually shows my lgt to the ogive with hunting and most match (Sierra, Nosler, ect) to be within a couple thousanths at the most. A slightly high primer will skew things.
 
I will have more time tomorrow, to nail down more exact measurements, I'll also check the primers.

I guess if I sorted by the ogive, after I had them loaded, I'd be better off.

Thanks guys !

Jim
 
Jim,

I've found that you need to wiggle cases a tad to get a final reading on the rig I use - just to make sure that the base of the case is square with the vernier jaw. I should use the case base device that was included when I bought the gear, but I misplaced the bugger years ago. Of course, I would end up with no correlation with the reading taken when I used the jump testeing doover if I went that route.

John
 
Jim D said:
First I sorted 100 bullets by their ogive. about half were real close.

I then began seating these into charged casings.

I proceeded to measure the ogive again including the case, now I had variation in the ogive again.

The distance between the tip, and the ogive was the culprit.

I have'nt fired any of these, but I fear the varied distance from the lands will give me varied results.

Does anyone make a seating die that contacts the bullet at say the ogive, and not just the vary tip of the bullet ?

I'm just trying get a grip on some variables !

Thanks for any and all imput !

Jim
Click to expand...

The problem is Jim, you are not seating the bullet at the same point on the ogive as you measured with the Stoney Point. The distance from the tip to land diameter on the ogive is not that important. It will be inside the bore and has little to do with the interior ballistics. The Stoney Point ID for .223 should be .217 or land diameter. Your bullet seater is more than likely some what smaller. The profile of the ogive can be different from bullet to bullet and the seater plug will be touching at whatever diameter it is. Sounds like you need a micrometer head on your seater die so you can make adjustments one round at a time. Another option is to seat them all long with just a little neck tension. They will all seat to the same length as the bullets touch the lands.

D R
 
I agree with DR. You're measuring the ogive at a different location on the bullet ogive. As Jim mentioned, the seating stem contacts the bullet where it can operate without deforming the bullet in any way.

I recommend an easy fix that will help you get more consistent seating (based on measurements back from the bullet ogive). After you decide on a particular bullet, you can lap its shape into the tip of the seating stem. That avoids marking your bullets, and you should get more consistent seating depth.

Avoid mixing bullets from different lots. Your groups will prove that you can measure your assembled handloads back from the ogive, and you'll get a noticable improvement in accuracy when it's consistent. If your "bullet" measurements vary within the same lot, you might want to try using a different bullet.

(Read our website for more tech tips on this subject.)
www.larrywillis.com

- Innovative
 
Thanks guys for the Great imput !

Thanks Larry for the link, I really like your digital headspace gauge !

I got out my S.P. comparator and did some checking.
First the Vmax were fine, the ones I had trouble with were old Remington hollow points.
After checking the COL, I had variation that compared to the ogive difference.
In conclusion, the problem lays in the seater to bullet fit.

I had a .0044 variation in 35 loaded rounds. I sorted out ten long, and ten short.
The next time I go to the range, we'll compare !

Thanks again !

Jim
 
Bullet Anatomy

OGIVE = the curved forward part of the bullet

SHOULDER = the junction between the ogive and the bearing surface

BEARING SURFACE = that portion of the bullet's outer surface which directy contacts the bore.

I assume you really want to seat the bullet to where the "shoulder" is in the same place everytime; therefore the length from the tip of the bullet to the shoulder does not mean a thing.

As stated the "seating stem" is most likely the biggest problem; if the tip of the bullet touches or bottoms out in the seating stem while seating your bullets. Modify the seating stem to prevent this from occuring. Which might be a simple drill and debur operation.

This problem usually occurs with long pointly bullets and not with the regular "chubbies"
 
Modified post

John S .......

I modified your post to be more accurate (below.)

---------------------------------------------------------

OGIVE = the curved part of the bullet.

SHOULDER = the angled part of a rifle case (just below the neck).

BEARING SURFACE = that portion of the bullet's outer surface which directy contacts the bore.

Seat the bullet to the same depth everytime. Compare loaded rounds (measured back from the ogive) for more uniform handloads. The length from the tip of the bullet doesn't mean much, except for how it fits in your magazine.

As stated the "seating stem" can be a problem. The tip of the bullet doesn't touch the seating stem while seating your bullets (and it's not upooused to). Modify the seating stem shape to prevent match the bullet shape. That prevents deforming the bullet during the seating operation. That's a fairly simple deburring (or lapping) operation.

This problem usually occurs when seating any bullet, unless its shape just happens to match your particular bullet - not likely.

- Innovative
 
NO I am talking Bullet!

Larry,

Yes the cartridge case has a shoulder; but I am taking about the bullet.

REFERENCE: Sierra Bullets

WE ARE TALKING ABOUT BULLETS! NOT CARTRIDGE CASES!

I am not corrected, please re-read the post, I said nothing about the cartridge case.

Common bullet parts:

Meplat, ogive, shoulder, core, bearing surface, jacket (except for solids, which I believe includes lead) heel, base and sometimes boat tail and now the common acetyl resin tip or other such stuff.
 
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I must have been confused when you said .......

SHOULDER = the junction between the ogive and the bearing surface
Click to expand...

......... because a rifle bullet has no shoulder.

- Innovative
 
No confusion Larry

Once again I am talking bullet anatomy.

SHOULDER "the junction between the ogive and the bearing surface"

Sorry Larry that is the term used "Shoulder" in the anatomy of a bullet.

Good grief man don't believe me, but go look it up or call Sierra Bullets 1-800-223-8799.

But then again when I used the term "anatomy" you most likely thought I was refering to the human body; which has a couple of shoulders.
 
Wilber .......

No. The bore groove diameter and the bullet diameter are the same (within a tolerance in the ten thousandths). A modern day conical shaped bullet has a bearing surface that transitions directly into the ogive. There is no "shoulder" on a bullet, unless you're referring to a semi wad cutter.

- Innovative
 
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