Concentric bullet seating - tolerances?

Jerry, I think you are on to something.

I tested different bullets with different preasure rings (going from .243 to .24375) and with the "bad die" the bigger the bullet resulted in bigger out-run. The good die, however, reduced this also with the bullets with the biggest preasure ring meaning the run-out was kept below 1/1000''. And for the record, the neck tension was the same. I do not have a very good explaination for this other than there is differences between "good" and "bad" dies?



Vern said:
Let us know the results of your day at the range.
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I will.
 
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I'm watching the thread with interest. Its quite interesting and the opinions are good.
I haven't seen anyone mention having a seater die made with their chambering reamer yet.
Iv,e seen in catalogues that wilson is selling seater die blanks . How about having aseater die made with your chambering reamer? Turning the bases on cases makes some sense. Isn't the point of making match ammo, ammo that is true and square, loaded right on, and cases that are near perfect? I thought we were looking for Zero run out on the loaded rounds.
 
I have been at the range today, dispite conditions being non-optimal it was still possible to do some testing. I might not be able to conclude "without reasonable doubt" however I am pretty sure what I will do with my "bad" seater - that will undergo Ratigans water test...

I did a total of 6 groups today, 3 groups with "bad seater" and 3 with the good one. Neck tention is the same, amount of powder is equal and seating depth is identical. In addition I shoot the groups without knowing what brass I was using by making 6 boxed of bullets (sighters included) and marked the boxes in the bottom, changed all of them around before I started shooting, in this way I should have excluded all mental influcese as well.

The two best groups were shot coming from the good die, the third best came from the "bad" one and the forth came from the good. Group 5 and 6 both came from the bad die. Is this enough to conclude completely? Perhaps not - but it will bring some extra piece in my state of mind when shooting hence the old die is currently at the bottom of a local lake, and the main reason for this is not that the groups were much bigger, but I get some variation I cannot really explain in a good way. Not much, but it is there - and that has been some of the story of my shooting this season: shooting the remaining shoots "in between" the others ...

I would like to add that the new Wilson Seater fits my brass slightly better meaning that the internal diameter is slightly less (about 0,0005'').

I will do a test or two more trying to make myself even more certain that this was worth doing, but so far I feel confident enough that I have found a track worth going.
 
I'm reading the replys One new shooter that i know is straightening his loaded ammo and doing quite well.
I'm not sure what his readings are . I have done that a long time ago. Currently the best groups from my best shooter likes to jump quite a bit. That said i would hope my ammo is a straight as possable. I remember when the whole neck turning thing came into Vogue. Some people just sorted cases back then. Then the neck turning started and the groups got smaller as time went on. I'm still thinking the custom seating die. , even though my ammo is pretty straight with some of my different seater dies. 2 wilsons and a neil jones.
 
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I believe the warehouse results however it was a long time ago and many things have changed now days.
If you want your own ware house testing go to Gene's tunnel. I am still waiting to do that. Maybe this off season.
 
Dear Pete,
how do you sort your bullets in order to get such a stringent overall lenght?
I tried to pm you as it is not strictly on topic but it was refused
sincerely
Filippo
 
FilippoMo said:
Dear Pete,
how do you sort your bullets in order to get such a stringent overall lenght?
I tried to pm you as it is not strictly on topic but it was refused
sincerely
Filippo
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I use a Tubb bullet sorting comparitor. I bought it several years ago and hav 5 years or soe sorted every bullet I have shot in competition over the past 5 years or so. Other companies sell bullet comparitors for less than I paid for the Tubb.

The problem lies with seating stems. All I am aware of are too small. The seating stems should touch the bullets close to where the bullet will touch the lands. This would eliminate sorting. One could load at random from the box without concern.
 
Goodgrouper, I believe, but could be wrong, that the targets and reference in your
previous post were from TJ Jackson. He was refering to the runout at the base of the brass.
This as he found was from poor uniformity in lower case walls of Rem. BR brass. Depending
on the concentricity gauge used, it can have an effect on the readings. Normally, that area is
outside the chamber, and has little effect. Its just ugly
 
As a matter of fact Jackson was convinced that merely turning necks was not enough, since the centerline of the ID of the unturned case neck is out of alignment with the centerline of the case body by half the TIR of neck thickness, and turning the OD of the neck does not change this situation. To get around this, he would first bore the inside of the necks so that they were concentric with the CL of the case body, as measured from the outside, and then turn the OD of the necks. As Bob said the picture was to show that given the minimal clearance between Benchrest cases and their chambers, that body thickness runout, near the case head is of little importance.
 
The problem lies with seating stems. All I am aware of are too small. The seating stems should touch the bullets close to where the bullet will touch the lands. This would eliminate sorting. One could load at random from the box without concern.
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Pete, I don't know if you want to do this, but Joel Pendergraft and I pretty routinely dial in the stem of our Wilson seaters in the lathe, and with a small end mill, drilll, or boring bar, bore out the stem so the resulting contact with the bullet is low on the ogive of the bullet. We're just making clearance in the original stem, trusting that the original hole/angle is correct.

Easy enough to do or have done.

Not sure it would matter, but if you wanted, and if your tooling was up to it, you could use a small carbide boring bar -- these guys are a little expensive -- and set the angle on the cross slide to both get a little more contact on the bullet, and ensure that contact is concentric to the outside of the stem.

Uniformity of bullet jam when seating is of course increased. This probably only matters if you use a seating depth in the +/- .010 region.

FWIW
 
The bullet will be sitting at an angle to the bore when it's floating free in the neck just before it starts it's travel up the bore. This angle will be determined by the clearance in the neck, expanded by pressure, and also by the difference in deformation caused by the lands from one side of the bullet to the other. This difference in deformation will be influenced by bullet run out. The deformation of the bullet will not differ by a large amount from side to side and if neck clearance is low the angle will not be great. The point is, initial run out had only a minor effect on angle of the bullet to the bore when it begins to float free in the neck. Several shooters have confirmed this by actually shooting bullets with high run out.
 
Pacecil,
Published (and unpublished) evaluations of the apparent lack of importance of runout may reflect an over simplistic approach. If the neck and throat clearances are small, and the neck thin, as are typical in Benchrest, bullets that are seated to engage the lands, which show an initial runout that is relatively large (in one published account .004) are straightened as they are chambered. This may be verified by removing the loaded round and remeasuring. Shooting good groups with crooked ammunition, with a chamber and seating depth like I described, should probably not be used as a guide for the results that would be obtained when jumping bullets, or a chamber that has a larger throat diameter. I think that one needs to look at the procedure before accepting a pronouncement as having universal application. When I tested the runout, after chambering, of a round that I had "unstraightened" to around .004 TIR it was .0015, this with the conditions that I described above.
Boyd
 
CharlesE,

I use Forster Ultra seaters and tried to do what you discribed but broke through the stem before I was able to advance the seater. I think either I have to make the right one for them(my dies) or use the .375 shortened slightly. I find it amazing that the die makers and others haven't noticed this problem before. Of course, if one Jams and fools with powder, they never notice.

A better fit of seater stems could allow anyone to shoot bullets made in different machines or by different people and retain the same accuracy; I think, anyway.
 
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pacecil said:
The bullet will be sitting at an angle to the bore when it's floating free in the neck just before it starts it's travel up the bore. This angle will be determined by the clearance in the neck, expanded by pressure, and also by the difference in deformation caused by the lands from one side of the bullet to the other. This difference in deformation will be influenced by bullet run out. The deformation of the bullet will not differ by a large amount from side to side and if neck clearance is low the angle will not be great. The point is, initial run out had only a minor effect on angle of the bullet to the bore when it begins to float free in the neck. Several shooters have confirmed this by actually shooting bullets with high run out.
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I don,t disagree with what you say, however your explanation seems vague, in terms of great
and small. That gas flow would tend to equalize and center the bullet as it floats in the neck
is acceptable. I do however think that a bullet that is seated quite long in a long throat is much
more able to center ,being far less influenced by the neck. I also think that a bullet in hard contact with the lands, is much more commited to its error than one in not so firm contact,
such as .008 off of jam. It also seems that fb bullets with the common pressure ring have the
ability to shift on axis better than bullets without the pressure ring. We can of course have
errors of concentricity on two plains. One being axial and the other radial. Its all about dies.
 
To Bob Kingsbury and others......

First, I don't think it has been made clear in this whole thread that run-out as measured may be indicating either angular misalignment, or eccentricity. Second, I have assumed it is in fact an angular position of zero degrees of bullet to bore is what everyone is trying to achieve.

The factors you mentioned; long throat, hard contact, pressure ring, are not important to what is happening here. Others have brought up things such as; base squareness, ejector springs, brass thickness, extractor loads, these also mean little or nothing. What is all important is the angle of the bullet in the throat.

Gas flow might tend to center the bullet base, or perhaps the whole bullet, but there could also be flow and pressure conditions that would tend to push bullet to side. In any case the position of the bullet base is one of the things that determine bullet angle in throat. The other point that establishes the angle is the contact at the front of the bullet.

What I was trying to point out is that contact with the lands, or bore, at the nose of the bullet plus contact at the bullet base with the neck is what establishes the angle. Initial run-out of the loaded case, or all the things mentioned above, will have no, or at best only a minor, influence.
 
Yes, but if you want angular alignment that is better than a given setup will self correct to when the bolt is closed, you will have to get it from the dies. From there we go to the question of at what point does angular misalignment start to show up on the target. Good luck with that one.
 
Pacecil, It is agreed that the angle of the bullet in the throat is all important. What I need to
know is, why does initial runout have no, or minor effect. We cannot always seat bullets
in solid contact with the lands. We do not contact bullets at the front even when seated
in contact, but rather as far back as just over one caliber from the base. What would cause
them to self align in this less than ideal situation.
 
Bob, if I understand correctly, Pacecil is suggesting that runout is a non-issue because the neck relaeases the bullet to it's fate, before the bullet moves. Once free from the neck caused misalignment, other factors might come into play.
But two big questions I have:
1. Has anyone demonstrated that runout detriments performance? With something other than a point blank gun?
2. How does seating distance relate (some best jammed, some best off)?
 
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I don't understand the questions about this. If you stick any cylinder shaped object into a bore slightly bigger than the cylinder, it's going to contact either along one side , or it's going to hit at front and rear opposite points. This determines how axis of the cylinder aligns with axis of the bore.

I could put a bullet into the throat with out ever having had it loaded into a case (the way they loaded them in Pope's time). It would come to some angle in the throat depending on clearances. This is what determines the angle the bullet is going to take when it proceeds down the bore, not how it might have been loaded into a case
 
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