Some bullet measuring numbers

[LVLAaron]

Warning: This is just data. No conclusion to be shared. Don't fight me.


Some friends have started testing with the Accuracy One Seating Depth Comparator. The idea is interesting to me, but I have doubts in my mind about where and how it's making contact with the bullet. I figured that depending on where you measure a bullet would affect how much variance you get across a set of bullets.

So I took 4 measurements across 10 random berger bullets from a brand new box.


Measurement 1: Measured with the Short Action Customs comparator tool.
Measurement 2: Hornady 30 cal comparator tool
Measurement 3: Hornady 6mm comparator tool (to measure further up the bullet)
Measurement 4: Using a wilson 30 cal inline seating stem as my comparator


Numbers at the bottom are the spread.

 

[whatsupdoc]

What is the bore diameter of the SAC tool?

 

[piie]

Warning: This is just data. No conclusion to be shared. Don't fight me.


Some friends have started testing with the Accuracy One Seating Depth Comparator. The idea is interesting to me, but I have doubts in my mind about where and how it's making contact with the bullet. I figured that depending on where you measure a bullet would affect how much variance you get across a set of bullets.

So I took 4 measurements across 10 random berger bullets from a brand new box.


Measurement 1: Measured with the Short Action Customs comparator tool.
Measurement 2: Hornady 30 cal comparator tool
Measurement 3: Hornady 6mm comparator tool (to measure further up the bullet)
Measurement 4: Using a wilson 30 cal inline seating stem as my comparator


Numbers at the bottom are the spread.

Re-do your test with another brand of bullets of the same calibre and you will probably reach a different conclusion?

 

[LVLAaron]

What is the bore diameter of the SAC tool?

~ .304

 

[LVLAaron]

Re-do your test with another brand of bullets of the same calibre and you will probably reach a different conclusion?

I don't have a conclusion for this brand.

 

[piie]

I don't have a conclusion for this brand.

You tricked me by adding that word to your disclaimer - what I meant was you will probably find that each of these tools will "seem" to produce "more accurate" results than the other depending on which type of bullet you measure.So while you tested on one particular bullet, it "would appear" that the H3O has a more "consistent" measurement - I would postulate that if you were to use another brand of bullet that has a different ogive shape - one of the other brands may appear to be "more consistent" - you have the tools - would be interesting to see the results if you would humour me wth your time

 

[LVLAaron]

You tricked me by adding that word to your disclaimer - what I meant was you will probably find that each of these tools will "seem" to produce "more accurate" results than the other depending on which type of bullet you measure.So while you tested on one particular bullet, it "would appear" that the H3O has a more "consistent" measurement - I would postulate that if you were to use another brand of bullet that has a different ogive shape - one of the other brands may appear to be "more consistent" - you have the tools - would be interesting to see the results if you would humour me wth your time

I would agree. And will test on some SMK's I may have laying around.

 

[CA_Shooter]

Warning: This is just data. No conclusion to be shared. Don't fight me.


Some friends have started testing with the Accuracy One Seating Depth Comparator. The idea is interesting to me, but I have doubts in my mind about where and how it's making contact with the bullet. I figured that depending on where you measure a bullet would affect how much variance you get across a set of bullets.

So I took 4 measurements across 10 random berger bullets from a brand new box.


Measurement 1: Measured with the Short Action Customs comparator tool.
Measurement 2: Hornady 30 cal comparator tool
Measurement 3: Hornady 6mm comparator tool (to measure further up the bullet)
Measurement 4: Using a wilson 30 cal inline seating stem as my comparator


Numbers at the bottom are the spread.

.9810 on the Wilson stem seems like an outlier. Maybe remeasure that entire row?

The difference on the Wilson vs the others seems very out of whack

 

[LVLAaron]

.9810 on the Wilson stem seems like an outlier. Maybe remeasure that entire row?

The difference on the Wilson vs the others seems very out of whack

Measured multiple times to confirm.

 

[RegionRat]

That one sample skewed the results like @smoketheclay points out, but in general those results look typical in my experience.

It doesn't take much damage or error in some examples to really throw a measurement value when there is an amplification at work.

When you think about it, looking at the longitudinal component of a surface that is slanted means that the sensitivity will be affected by the slope. The steeper the surface where the measurement is being made, the more sensitive the longitudinal dimension will be to a change in diameter, so a given profile error on a bullet will mean different things based on where along that profile a round gage is used.

We used a measurement system called a Federal Formscan to do the metrology on these shapes. The machines are very good but also very expensive. You would typically only see them in high end labs. As time passed, some labs would try and do more sampling with their CMM machines, but they couldn't equal the Formscan performance when it came to surfaces of revolution.

Nice work and thanks for posting your results.

 

[LVLAaron]

That one sample skewed the results like @smoketheclay points out, but in general those results look typical in my experience.

I'm glad it's there, to be honest. Because it helps lead to the next part of the conversation.


Which datum point is the "right" point to be measuring, when checking seating depth?

 

[RegionRat]

"Which datum point is the "right" point to be measuring, when checking seating depth?"

Here you will get all sorts of opinions... so I'll throw out a statement and let the show start.

As long as you specify the diameter and chamfer of the gage tool so the values are not completely arbitrary, you are good enough.

Where standards exist, the dialogue is more clear. Those gage anvils have to be very precisely defined in both diameter and corner geometry for the results to translate. For example a razor sharp edge versus a chamfer. Then the gage force has to be controlled as well.
When numbers get thrown around without that reference diameter and chamfer, it just adds noise and leads to arguments over nothing.

I personally don't get too excited about these numbers needing to be transferable. Unless the ammo is being fed into a context where the chamber reamers have been standardized, the numbers are arbitrary anyway. A gross view of jump sensitivity is "good enough" in most discussions. Trying to get what we called "inter" and "intra" lab round-robin values to agree was a waste of time when there wasn't a standard definition of the gage method, so I don't recommend you spend too much resource on things that don't suit your own needs.

Checking a bullet batch for stats within the batch is one task, then checking against a different batch is another. So just checking for consistency in bullets is much easier than trying to check jump between different rigs. If you keep track of your gage anvils, and make sure you don't damage them, you should be able to tell if a new batch of bullets is a risk.

I suggest that you find the best of your own tools and gages that help with controlling your seating depth for your process, and don't worry about those who will claim theirs is better. Getting state of the art accuracy is expensive, and trying to mass produce it is even more expensive. When you tune your load to your rig, you have done more than most Government committees ever have.

 

[Straightshooter1]

Warning: This is just data. No conclusion to be shared. Don't fight me.


Some friends have started testing with the Accuracy One Seating Depth Comparator. The idea is interesting to me, but I have doubts in my mind about where and how it's making contact with the bullet. I figured that depending on where you measure a bullet would affect how much variance you get across a set of bullets.

I figured the same thing as I contemplated how I might go about getting the most consistent results. Of course, it doesn't really matter which comparator one uses as long as one uses the same one for measuring the bullets and seating depth. However, after seating my bullets I wasn't satisfied the the variances I was getting. My goal was to see if I could stay within +/- .001 in seating depths. So my first step was to sort through the box of 500 into groups having +/- .001 range. Then after seating, I'd still get too many for my goal that were outside that range I was looking for. Neck tension was a big deal that affected it and when I went to annealing after every firing, that helped a lot. But I still wasn't satisfied. So looked closer at the difference between my Wilson seating stem and my comparator which had quite a large difference (I'm talking about a .30 cal comparator). I decided to get a comparator that makes contact with the bullet at (or very close to) where my Wilson seating stem makes contact. I sorted my bullets with that comparator and now when I seat my bullets I get very consistent seating depths rarely at or over the +/- .001 that I look for.

I was going to get a custom comparator to match the Wilson seating stem, but I found a small caliber comparator that matched the contact area of the seating stem.

For measuring my distance to lands, I still use the standard Sinclair comparator insert as I find its diameter close to the diameter of the touch point on the lands.

BTW, I use mostly SMK's for most of my shooting and Bergers when going long distance. I alway sort my bullets unless my sample measurements happens to show they're within +/- .001.

 

[LVLAaron]

Here's my personal take.

When measuring distance to the lands, I understand that this is just a reference point. So whatever tool I decide to measure with, is what I will always measure with.

What made me start this little project was the "Accuracy One Seating Depth Comparator"

If you're using the Accuracy One tool, you're measuring a different datum point than your seating die uses. And knowing we have variation of a thou or two from tool to tool and datum point to datum point, I don't see the benefit of seating bullets, and then using the accuracy one tool to sort bullets.

Anyway... Not saying anything bad about the tool. I have ordered one as well as many other tools from the same company. Just wanted to start a dialog about it.

Aside from the accuracy one tool... I think I want a comparator that uses the same insert profile that my seating die uses.

 

[RegionRat]

One thing I would recommend, is after you study your bullet batch, pull out and save a reference bullet and keep it as a calibration sample. I even like to save the "bad" or heavy/light samples in case I have to change measurement methods.

Using that will let you understand if the current batch has a QC issue or a design change. If you live long enough, you will see that dies at bullet factories wear out and once in a while the new ones aren't the same.

 

[BoydAllen]

Just as a reminder, the important thing (IMO) is the consistency of the distance of the loaded bullet from or into the rifling when the round is chambered. Because of variations in the curve of their ogives, the distance from where a seating stem makes contact and where the rifling will make contact vary within the same box of bullets. With perfect consistency in length at the seating stem contact, there may still be variation measured where, or near to, the rifling would make contact. I had not been familiar with the Accuracy One tool. It intrigues me, this because right before the powder starts burning, the loaded round is propelled forward to the point where the shoulder of the case is stopped by the chamber shoulder. It would seem to me that at this point, differences in shoulder bump just become differences in the gap between the case head and bolt face. This whole measuring from the shoulder thing has gotten my interest in a good way. For instance, I believe that trimming necks using the shoulder as a reference rather than the head may be superior to the traditional method.

 

[INTJ]

Here's my personal take.

When measuring distance to the lands, I understand that this is just a reference point. So whatever tool I decide to measure with, is what I will always measure with.

What made me start this little project was the "Accuracy One Seating Depth Comparator"

If you're using the Accuracy One tool, you're measuring a different datum point than your seating die uses. And knowing we have variation of a thou or two from tool to tool and datum point to datum point, I don't see the benefit of seating bullets, and then using the accuracy one tool to sort bullets.

Anyway... Not saying anything bad about the tool. I have ordered one as well as many other tools from the same company. Just wanted to start a dialog about it.

Aside from the accuracy one tool... I think I want a comparator that uses the same insert profile that my seating die uses.

Then you want George MacDonald's SO/CO tool. It measures bullets where the seater stem makes contact and where the chamber will make contact. This assures that all the bullets in the sort seat the same and are the same distance from the lands.

 

[newbieshooter]

Then you want George MacDonald's SO/CO tool. It measures bullets where the seater stem makes contact and where the chamber will make contact. This assures that all the bullets in the sort seat the same and are the same distance from the lands.

picture here:

Sorting bullets, brass, and primers.

Faced with more time at home and less at the range for a few weeks, decided to get all my components ready for the 2020 shooting season. I know I should have done that last winter... I didn't. I have tested all three and can measure good improvement from all at 600 yards on target. I hope to...

forum.accurateshooter.com

and here:

SOLD - FS bullet sorting tool

Selling a bullet SO / CO measuring and sorting tool made for .243/6mm by George MacDonald. It is described in this thread - https://forum.accurateshooter.com/threads/sorting-bullets-brass-and-primers.4002419/ Paid $200. Will sell for for $150 shipped and I will include a tool made by Sinclair...

forum.accurateshooter.com

 

[LVLAaron]

One thing I would recommend, is after you study your bullet batch, pull out and save a reference bullet and keep it as a calibration sample. I even like to save the "bad" or heavy/light samples in case I have to change measurement methods.

Using that will let you understand if the current batch has a QC issue or a design change. If you live long enough, you will see that dies at bullet factories wear out and once in a while the new ones aren't the same.

I have a little library of baggies. Each one contains one of the average bullets and the lot lumber it came from.

 

[LVLAaron]

Just as a reminder, the important thing (IMO) is the consistency of the distance of the loaded bullet from or into the rifling when the round is chambered. Because of variations in the curve of their ogives, the distance from where a seating stem makes contact and where the rifling will make contact vary within the same box of bullets. With perfect consistency in length at the seating stem contact, there may still be variation measured where, or near to, the rifling would make contact. I had not been familiar with the Accuracy One tool. It intrigues me, this because right before the powder starts burning, the loaded round is propelled forward to the point where the shoulder of the case is stopped by the chamber shoulder. It would seem to me that at this point, differences in shoulder bump just become differences in the gap between the case head and bolt face. This whole measuring from the shoulder thing has gotten my interest in a good way. For instance, I believe that trimming necks using the shoulder as a reference rather than the head may be superior to the traditional method.

That's why I made the switch to the short action customs tool. It measures pretty far down the bullet compared to other tools.


Your thinking on the accuracy one tool is what my friends are saying as well. It makes sense. Real world testing will tell us if it's a worthwhile tool.