Bullet RUN OUT

I have had all of those thoughts too

What appears to be happening is the size of the ogive, where it touches the lands changes in comparison to the size of the ogive where the seating stem touches it. Certainly the length of the straight surface of a bullet would have no bearing on seating depth. I think the term Bearing Length is one that is used because there hasn't been one thought up for the variation in the ogive surface length and width. Thinking about it, the entire problem lies in the ogive length. For sure a seater stem isn't going to change and for sure, if one pushes a bullet into a case with the same seater stem and the end result is .002 or .003 longer or shorter, when measured with a comparitor near where the bullet will engage the lands, the problem can only be the length of the ogive surface. Why that varies is the question.

Apparently the comparitor used to measure the "Bearing Surface" finds a direct relationship between the base of the bullet and where the bullet will touch the lands and then the seater stem will follow and give that variation when seating that bullet.

Bottom line for me is this; now that I have segregated my bullets I can set up my seating die for an exact seating depth and get it, round to round. If I were to just randomly take bullets from a box, the way they come in the mail, I will have variations in OAl where the bullets will touch the lands.

The sorting method works for me. The rest of you guys can approach this any way you like and ignore what I have lain out here if you want to, It's ok by me. I want consistent OAL's. I have found a method to achieve them. How you guys want to "Splain " it is up to you. I have my thoughts on the subject, they are justified in my method of sorting bullets and that is all that matters to me. Perhaps I am wrong but I do get consistent OAL's now. This seems to be a discussion not unlike rather or not a few powder charges that have .5 less powder in a box of loaded rounds is acceptable. Neither using thrown charges nor loading with random bullets is acceptable to me. I want to make my loads as good as I can make them. I need all the help I can get!
 
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Some time ago while having a conversation with a gunsmith/Benchrest competitor about this very problem, (variations in seating depth as measured with a barrel stub), he mentioned that a new shooter had been having problems that were ultimately traced to that as the probable cause. What he did to improve the situation was to reshape the cavity of the seating stem so that it made contact with the bullet as close to where the bullet would eventually touch the rifling as possible. In other words the circle of contact between stem and bullet was moved down the bullet, to a point closer to the shank. This seemed to help.

While on the subject of runout and seater stems I will also mention that in an old issue of PS Merrill Martin once wrote of improving loaded round runout (straightness, sometimes referred to as concentricity) by reworking the cavity of a Wilson seater stem so that it was more concentric with the OD of the stem. He did this with a small four jaw, and boring bar, I believe. In the pursuit of straightness, this is an area that mostly goes unchecked. Maybe more attention should be paid to this detail.
 
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I would agree on both items

Boyd Allen said:
Some time ago while having a conversation with a gunsmith/Benchrest competitor about this very problem, (variations in seating depth as measured with a barrel stub), he mentioned that a new shooter had been having problems that were ultimately traced to that as the probable cause. What he did to improve the situation was to reshape the cavity of the seating stem so that it made contact with the bullet as close to where the bullet would eventually touch the rifling as possible. In other words the circle of contact between stem and bullet was moved down the bullet, to a point closer to the shank. This seemed to help.

While on the subject of runout and seater stems I will also mention that in an old issue of PS Merrill Martin once wrote of improving loaded round runout (straightness, sometimes referred to as concentricity) by reworking the cavity a Wilson seater stem so that it was more concentric with the OD of the stem. He did this with a small four jaw, and boring bar, I believe. In the pursuit of straightness, this is an area that mostly goes unchecked. Maybe more attention should be paid to this detail.
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A stem that was contacted the bullet near where it was to seat in the lands would be great and may eliminate the need to sort bullets. I would think many or most folks do not check the concentricity of their stem. Many of us do not have the facilities to do so. I bought a Micro mini lathe last winter and just found out that there is around.007" of runout in it. It would be tought to check a stem in that, eh?
 
Good shot Boyd

That's the missing piece. If the point of the bullet bottoms out in the seater stem, everything I wrote is void.
 
Al,

Al Nyhus said:
With bullets from the same point die, the relationship from the lands to the bullets ogive on a seated bullet does not change regardless of how much the base-to-ogive figure varies between bullets from that same die. The only thing that will change is where the base of the bullet ends up. -Al
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aren't you assuming that the ogive contact on the bullet for the seating stem remains in the same place on the bullet?
 
In all the seating stems I have seen

Wilbur said:
That's the missing piece. If the point of the bullet bottoms out in the seater stem, everything I wrote is void.
Click to expand...

The releif hole going up through the center prevents the tip of the bullet from being able to touch the stem. Whatever is going on is happening down near the end of the taper of the ogive. it must be that there are variances down there, not up where the seater stem contacts the bullet. That would account for the base to ogive length difference corelating to the seating depth differences I think.

I had a lot of bullets that were made 2 or 3 years ago that had a total variation of .012". Most of the bullets in any lot will be within .001 of each other but, like the Bell Curve in any lot of anything, there will be different sizes on both ends. Some of them vary greatly and some don't. One lot I purchased last year were about evenly split .001 apart for the lot. The best ones I have seen were exactly the same but it was only a lot of 100 sent to me to test.
 
This statement is

Al Nyhus said:
With bullets from the same point die, the relationship from the lands to the bullets ogive on a seated bullet does not change regardless of how much the base-to-ogive figure varies between bullets from that same die. The only thing that will change is where the base of the bullet ends up. -Al
Click to expand...

Not true, in my opinion, from what I have experienced. There is a difference in the size of the ogive near where it touches the lands and seems to be more in corelation with base to ogive than it does from where the seater stem touches to where the bullet touches the lands. Lots of us agree on this one.
 
bullet run out

sorry to but in .
but years ago wison noted lapping in the die stem on their seater for one particular bullet. that way you had the same contact each time.
So maybe each different bullet shape needs a seater punch lapped in.
 
How would variance in bearing surface make any difference?
Does your comparison include a portion of the ogive, or does it show only bearing to base?

My thinking has always been that ogive radius varies, and that comparison with a seater stem(instead of a stub) would indicate same seating depth. But followup comparison with a nut, or stub(at ~.236) might still show variance.
If this variance is showing up with bearing comparison, then that check must also include a portion of the different ogive radius. IAW, it's not a true bearing comparison, but still useful.

I built a prototype 'ogive radius comparator' for this check specifically. Someday, my machinist will finish the tool for me(hopefully). But use in it's rough form comfirmed for me that ogive radius variance is as real as bearing and meplat variance. This was with secant ogive bullets though.
Maybe someone here could help with further development..

Great discussion!
 
glp said:
aren't you assuming that the ogive contact on the bullet for the seating stem remains in the same place on the bullet?
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Yes, I am Greg. :) That's why I wrote: "With bullets from the SAME point die...." in my post. Wilbur and R.G. made the same point. Might be a pun, there. :D

If you are comparing 7 ogive bullets to 10's, or secant ogives to conventional tangent ogive configurations, or VLD types to either of these two, the place on the bullet where the seater stem contacts the bullet may or may not be different.

I'm making the assumption that a person has made sure the tip of his bullets aren't bottoming out in the seating stem, as is common with the VLD style bullets in conventional seating stems.

Tonight, I took a couple of my 117 gr .30's...one with a base-to-ogive figure of .420 and another from the same point die that measured
.370, seated them using the same seating stem length and then measured the case head-to-ogive.

How much difference should there have been, given the .050 base-to-ogive difference of the two bullets? -Al
 
they should be

the same seating depth were they?
My logic goes with your thinking Al but i was wrong once I'm going to try it with same boooollet different batch.Jim
Then again I don't know how many dies the maker uses?
At least you know your using same dies.
Thanks Jim
 
Here Is What I Did

I machined a piece today that locates on the same spot as where the land marks appear on a Bruno Boatail. I then took 100 bullets, and using this tool, measured from the base to the end of the gage. I could not pick up .0005 in all 100 bullets.
I periodically check loaded rounds at matches, using a similiar tool that does locate further up the point. I can't ever remember finding any that varied at all.
Of course, Lester makes all of my bullets on the same run, with the same lot of jackets, at the same time, and of course, out of the same die.......jackie
 
bullet run out

I see there are different views on this.
One is more or less checking one part and others a different part.
Here are a few things i have observed.
Making bullets is an art form just like lapping a barrel.
The operator is the one who determines what happens at the pointing.
The die must be set correctly to get the most uniform bullet at the base , pressure ring and point. The cored jacket must move at the same rate.
by this i mean { the stroke and pressure at the handle must be the same each time. Core seating is one of the keys. Each core must have the same weight or very close to it.1/10th grain. The core is swaged on the pointing
operation also. that core is final formed in the point up.
quality control is the key. I double bump my cores.
once to make the air escape the second to seat the core.
The lube is also a factor how much and where. Too much and you have swag marks on the nose . too little and the bullet scrapes the die walls.
Uniform cores= uniform core seating. uniform core seating = uniform
point forming. It's that simple. The jackets are lubricated best just as they come out of the core seater. Quality bullets are made on Quality
dies. Trying to make great bullets on poor dies is a waste of time and money. It's not rocket science just good quality control, and a lot of pride in the finished product. thank your lucky stars that you have good bullet makers and people willing to make them.
 
I just measured

the depth of the releif hole in one of my Wilson stems, .675 deep. I them inserted a 7.5 ogive bullet in it, marked where the stem stopped and measured how deep it went into the stem, .375 or so. I then inserted a Match King type bullet and got the same distance reading, give or take. The meplat lenght ain't an issue.
 
Al Nyhus said:
Yes, I am Greg. :) That's why I wrote: "With bullets from the SAME point die...." in my post. Wilbur and R.G. made the same point. Might be a pun, there. :D


I'm making the assumption that a person has made sure the tip of his bullets aren't bottoming out in the seating stem, as is common with the VLD style bullets in conventional seating stems.

Tonight, I took a couple of my 117 gr .30's...one with a base-to-ogive figure of .420 and another from the same point die that measured
.370, seated them using the same seating stem length and then measured the case head-to-ogive.

How much difference should there have been, given the .050 base-to-ogive difference of the two bullets? -Al
Click to expand...

Al,
I'm not sure. If the point on the two bullets where the tapered nose meets full caliber diameter is at the same position on each bullet then the seating depth should be the same. I just don't see where the reference point for a loaded round can be any other point on the bullet than that one. If that varies among bullets due to lube or whatever other variable in themaking process then seating depth will vary by the difference between the positions. Am I missing something here? I think what you are saying is that this point will not vary among bullets from the same die? Thanks
 
I believe the issue is around where the seating stem contacts the bullet. On a certain lot of bullets the length from where the seating stem contacts the bullet and where the lands contact the bullet remains fairly constant for that lot of bullets. In a new lot, that distance will again be relatively constant but it is a different distance than the prior lot. Where the ogive ends up in loaded round depends on where the seating stem contacted the bullet. If that relationship between seater stem contact and the actual ogive of the bullet changes, you get different amounts of jam. I don't know enough about making bullets (actual next to nothing) to know why the relationship changes when the bullets are from the same maker/bullet die but it does and it causes differences in the amount of jam. Randy J.
 
I just figured out how to settle this.

If one has a "gizzy" (piece of barrel that has the front of your chamber reamed in one end, and has been squared to the bore on both ends), and one's practice is to seat bullets into the lands, one can simply insert each loaded round into the gizzy and measure from the case head to the opposite end of the barrel stub, recording the measurement for each round. That should tell us if differences in bullet shape from bullet to bullet, between seater stem contact area and leade angle contact area, has procuced a difference in seating depth. I load at the range for my PPC, so I don't have any loaded ammo to measure. If one of you has the parts and pieces handy to do this, please give it a shot, and tell us your results.
 
Boyd Allen said:
Some time ago while having a conversation with a gunsmith/Benchrest competitor about this very problem, (variations in seating depth as measured with a barrel stub), he mentioned that a new shooter had been having problems that were ultimately traced to that as the probable cause. What he did to improve the situation was to reshape the cavity of the seating stem so that it made contact with the bullet as close to where the bullet would eventually touch the rifling as possible. In other words the circle of contact between stem and bullet was moved down the bullet, to a point closer to the shank. This seemed to help.

While on the subject of runout and seater stems I will also mention that in an old issue of PS Merrill Martin once wrote of improving loaded round runout (straightness, sometimes referred to as concentricity) by reworking the cavity of a Wilson seater stem so that it was more concentric with the OD of the stem. He did this with a small four jaw, and boring bar, I believe. In the pursuit of straightness, this is an area that mostly goes unchecked. Maybe more attention should be paid to this detail.
Click to expand...


Boyd you struck a note. I have thought about why no one makes a seating stem that engages the bullet at the point it touches the lands. Seems like some of the die makers have missed something or maybe I have. In a Wilson type seater that is made for your chamber and a seating stem of this type would be something of interest.
 
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