Ogive Variance

L

Lynn

Registered User
I have been seating some 6mm bullets with a Redding competition seater that has the round sleeve that contacts the bullets way up on the ogive.
When I then measure the rounds with a comparator I am getting a few rounds 0.001 or 0.002 on either side of my desired reading but I am also seeing a few rounds that are way way out of spec.

How uniform are your ogives if you used a 22 caliber comparator and a 6mm comparator on the same bullet?
Lynn aka Waterboy
 
Lynn

You may be running into the same problem I had years ago, hope I'm understanding this right. But I measure ogive to ogive on the bullets with JB comparator then use sinclaire comparator on my calipers for OVAL. So if you're not using Moly in the necks you're going to get a variation in OVAL.
This may be the variation you are seeing. I believe my necks at tighter than most people like, so that is what I do.

Joe Salt
 
lynn, i am confused. your loaded round, base to ogive measurement is inconsistent? is the tip bottoming out in the seating stem maybe? this has been know to happen with vld's. if so chuck the stem up in a lathe and drill it out.
tom

i have allready drilled out my wilson 338 seating stem in preperation for the 338 bergers, please eric, thanks, haha.
 
Yes thay are very inconsistent when measuring from the casehead to the ogive with a comparator.The meplat has about 3/8 of an inch before it bottoms out in the seating stem and the seating stem is not split.I have had that happen in the past.
I just checked the length on some seated 103 Clay Spencers using the same seating die and the same measuring tools and the problem seems to have disappeared.
I am trying to get this batch of bullets ready for tipping and I want them sorted to within 0.001 in all groups before trimming and tipping.I may just stick with the custom bullets.
Lynn aka Waterboy
 
bullets gettin fat

Lynn...in the past Ihave had the same thing happen with Hornaday bullets...they seem to have jackets that are "softer" than other brands...not saying they are bad bullets,,just softer ...and if my neck tension was too tite or bullets were not coated ...they would swell at the tip and cause erattic measurements....this is another reason that A-max's need to jump to shoot best --IMHO,,,so try coating the bullets or lubing the necks or less neck tension....hope this doesnt muddy the water ....Roger
 
ogive variences

I have seen the same thing. I switched to a Wilson inline seater and I don't see it anymore. I have no idea what caused it, if anyone knows I would like to know as well.
 
maybe

Could it be that part of the problem is that your comparator tool is measuring a point on the bullet up from the ogive, the Wilson up further yet, and the Redding up on the bullet even more than the Wilson? So what you’re seeing is the difference in the bullet shape above the real ogive?
My Wilsons are more consistent than the same caliber Redding Comps that I have. And if I remember right the Wilsons all touch the bullet at a point closer to the ogive than the Reddings. Take the seater cup out of the die and hand turn a fine-wooled bullet around in it to see where it is pushing on the bullet. Do the same with your comparator. You may be surprised how far from your rifle’s lands marks the comparator is taking its reading from and how much further away the seater is touching the bullet. I hear the new Sinclairs are much closer to the real ogive than the old Stoney Points. But I heard one guy complain that his bullets were sticking in the new Sinclairs.
 
Lynn,
Is your Redding die set so that the body of the die bumps the shell holder. I know that this contradicts the instructions, but as long as you keep in mind that the die body is unhardened and dont get carried away, I think that you will be all right. This should load the press linkage and take out some of the spring, that could be partially responsible for the variation. Friends have seen the same thing. I think that arbor press type dies are less prone to this problem.
 
Boyd
My die isn't touching and the press is a very old pacific so the pin not running true is at the top of my list of things to check.

Tricrown has explained what I am seeing pretty well.

If you use a Redding seater and you pull the seating stem out and use it as your comparator you get one number with a given amount of variation.If you then use a regular comparartor that attaches to the caliper and rides further up on the bullet you get a second number as expected but the variation is even worse.
If you then measure the OAL of the loaded rounds forget about making any sense of it at all.
We sort bullets trim the meplats and then we point them but to my way of thinking if we are seeing this much variation in the bullets ogive the bc must either be varying all over the place.If true we need to order larger quantities in order to come up with enough bullets to shoot a full season.I started out with 2300 and after a months worth of work sorting them I may just shelf them and try a different bullet altogether in the hopes of more consistency.
Lynn aka Waterboy


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to explain further

I haven’t sorted this season’s bullets yet, but here’s what I got from bearing surface sorting a thousand 105VLD Thicks last year:
6- .462”
4- .463”
18- .469”
150- .470”
500- .471”
300- .472”
11- .473”
That may seem like a lot of variation to shooters that only work with the lighter shorter bullets. But it is actually pretty good for the longer high BC bullets. Thing is I was over 100 bullets into sorting them and ready to just shoot the things as they came until I ran into one of those 10 that are so much shorter than all the others. But even if you’re lucky and they all fall into .004” there’s no rule I know of that says the .004” variance will be equally centered at the same point on the bullet. So some bullets may have a .004” longer or shorter boatail and then a shorter or longer section above the ogive.

The 2 ways I can think of to skin this cat is to sort each size again using the base to ogive measurement or get yourself a 10 cal or so comparator made and measure from bottom of bearing surface to a point way up on the bullet. I also vaguely remember being in a conversation with a fellow shooter who said something about Bob Greene making a tool that does something to sort out this problem.
 
Tricrown You're doing the right thing by sorting bearing surfaces, know as long as you use the ones that are the same length and use the same measuring tool to measure your OAL and put them at the spot the rifle shoots best, now make sure you lube the inside of the neck they should all come out the same. You people worry too much about the length of the bullets not were they are to the rifling. When you change B.S. length that is more than say ten thou. Then use a dummy round to see if the OAL has changed. Any other questions call me 315- 342- 3088 Id be happy to explain it better on the phone. Takes me to long to type the stuff. Sorry!

Joe Salt
 
Lynn
I do not chime in very often but reading your post I see you are fighting the same monkey I did for some time. One thing that helped me was I machined another insert for the ogive measuring attachment on my calipers that matched exactly where the seating stem was contacting the bullet, all of my measuring and sorting was performed with the same insert. I still had the issue within the .001 - .002 tolerance as you are getting with an old Pacific press and die setup. In my opinion, for whatever it may be worth, is that there just are too many variables with that setup, i.e. the press stroke, and in my case, my frame of mind, neck tension, and annealed condition of the case neck that come into play. When I switched to a Wilson type in line seater things improved and as Joe mentioned lubing the case necks is very important. With all of these factors covered the only remaining issue that could be causing the variation must be related to neck tension. We all work on this brass to exacting precision but the amount that the brass springs after sizing will greatly affect the resistence of seating the bullet thus creating differences. I actually will seat sacrificial bullets in my brass and again sort my brass by these variations, resize and lube and reseat. Typically in the 2nd round the results are consistant.
 
Jess Thank you I'm glad someone is paying attention! The reason the lub helps I believe is not just neck tension, I think what is happening is the bullet is galling against the case going in. No rocket science just a little common sense. If you look on 6mm Benchrest Jason Baney wrote an artical after I explained it to him.

Joe Salt:rolleyes:
 
Jess
I have several presses and will give them all a try to see if I get any improvement.I did Boyd's run the ram into the die trick and didn't see much improvement.
I have the black powdered neck lube but quit using it after a can of it walked off my bench and left a huge mess.I was not fond of using it as everything and everyone turned black but if it would help I will give it a try.
I also have the Wilson micrometer seaters but only ever use them while testing at the range.They seem extremely slow when I'm at home but if they work/help I am willing to use them.I use a 1 gallon paint can opener to remove my cases from them while I'm at the range but if it works I'll have a slot milled into the die for easier access to the case.
Lynn aka Waterboy
 
Lynn said:
I use a 1 gallon paint can opener to remove my cases from them while I'm at the range but if it works I'll have a slot milled into the die for easier access to the case.
Lynn aka Waterboy
Click to expand...

I'm gonna' go out on a limb here........ you no doubt know this...... but fitted seaters typically have too much suction to allow you to get the case out without breaking the seal. You must pull the seater stem and the case will either fall right out OR you can push the seater stem back in and hydraulically eject the case, OR you can drill a bleed hole for the same purpose.

While this may not apply to your sitchyation it WILL keep a whole lot of other people from buggering up their seaters with screwdrivers!

And if and when a hand seating die actually IS machined so tight that the cases physically stick it's a simple matter to hone/polish it out.

I load at home with a hand seater and arbor press because I think it's the fastest way.

Neither method offers anything over the other far as accuracy IMO

al
 
Alinwa
I did it your way for 2 years on my 6BR's until I read the instructions one day and it said never to do it that way.
The paint can opener is pretty soft and fits very well plus it doesn't void the warranty.In my opinion Wilson should work on a protective coating to keep there dies from rusting then mill a access slot or drill some vent holes.They usually rust up before they ever wear out.
I'm just now going to try my other presses to see if it helps.The ram in my Pacific press is new old stock but the hinge pin is the original.
Lynn aka Waterboy
 
Lynn said:
Alinwa
I did it your way for 2 years on my 6BR's until I read the instructions one day and it said never to do it that way.
The paint can opener is pretty soft and fits very well plus it doesn't void the warranty.In my opinion Wilson should work on a protective coating to keep there dies from rusting then mill a access slot or drill some vent holes.They usually rust up before they ever wear out.
I'm just now going to try my other presses to see if it helps.The ram in my Pacific press is new old stock but the hinge pin is the original.
Lynn aka Waterboy
Click to expand...

Well I'll be jiggered!

Guess I better go read the directions :)

I agree on the rusting. I keep 'em in Flambeau or Plano clear plastic tackle boxes and spray them with oil. Same like reamers.

al
 
The Directions say don't pull it out all the way, and my directions say us moly inside your necks for better repeatable seating depth.

Joe Salt
 
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