Vern juenke machine

Wilbur said:
Did this fellow ever have a bad flier? I know I had one at the only 1000 yd match I shot...saw it hit the ground about 10 feet (at least) away. I don't know for sure but I think it was the wind that caused that one.

I think Lou's question is a good one as it is - what does this thing measure? He doesn't seem to care but would like to know given that it measures something. He just wants to know what it measures.....
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Well, Wilbur, those were my rifles. At the time you shot, I was "Juenke-ing" every bullet. And the brass would have been part of my normal set, neither new nor overly used.

I don't remember the day exactly (Do remember you drove your Cadillac, not the Caravan).

I think it as the wind -- believe I won MY relay that day ;-)

While I don't believe it was the day you shot, I remember one match where we had a strong wind that reversed. That day, we had a target come down during the sighter period, and by the time we got back to shooting, everybody's bullets moved 15 feet the other side of the target.

People go and look at ballistic tables, and note that a 10-mph wind will move a bullet a lot. With a 10-mph wind change, that'd be 52 inches (for a 187 BIB Flatbase, Doppler-measured BC of .526) at 1,000 yards, the HG you shot. My light gun at that time was a 6.5/06AI with 142 Sierras. Similar performance.

Truth is, you don't get that big a change very often. But when it does happen, particularly with a reverse, it's quite dramatic.
 
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Have you guys ever speculated, that if this infernal machine is generating an eddy current and measuring the variation of its flow, that it may be measuring the molecular density of the jacket material? Molecular density, or molar mass, is simply how porous an element or compound is. i.e. how well packed or how porous the element/material is.

For example, if you had a gallon bucket of softballs and a gallon bucket of golf balls both sets of balls being made of the same material, the bucket of golf balls would weigh more than the bucket of softballs. Why? Because there would be more air space between the softballs, hence less molar mass, or molecular density. Comprande'?
 
Jerry,
I also thought that it might be generating and measuring eddy currents. I had the use of one for a while, some years ago. At that time, I didn't have the equipment to really test the quality of bullets that were close. I do remember that I could not find a correlation between the readings and my groups, but as I said, what I was testing with was not up to the highest standards of short range benchrest. On the eddy currents thing, if someone put a cylinder of non conductive material on the machine, ceramic or plastic perhaps, I wonder if it would generate a reading. Also, I forget, does it show a reading before you start to roll the bullet? If it does not, that might reinforce the eddy current notion.
 
Boyd, if the device is in fact producing an electromagnetic field, where an eddy current resides-between the poles, it would be easy to take an object like a thin steel feeler gage petal and see if a magnetic field exists. Drivers, every day, that pass through intersections where traffic sensing lights are installed, pass through eddy current fields. That eddy interruption is what causes the traffic light to change. That may just be what Mr. Kuenke's machine is looking for, variations of field interruption caused by varying density of the jacket material???
 
Greg Walley said:
For what it is worth…A long time BR shooter and HOF member cooperated with me on a project by making a batch of 100 bullets; 36 were defective, and we mixed them with 64 proven excellent bullets made on the same dies and lot of jackets. The gross defects were as follows (six bullets each):

1. Scratching the ID of J4 jackets with a blunt carbide scribe before seating the cores
2. Shaving the sides of cores with a knife, then core seat them into J4 jackets
3. Poor uniformity of lube on the jacket before the final swage
4. Seated cores with insufficient pressure
5. Seated cores with too large of a punch
6. Seated cores with too small of a punch

I sent these bullets to a third party to check on the Jeunke machine, and he was unable to distinguish the good from the bad.

If there are any bullet makers here with a Jeunke machine, I would like to see them try to duplicate my experiment. Maybe others will get different results.

I think the unit measures something. Another long time BR shooter and HOF member put me on to an interesting idea some time ago that one can use the Jeunke machine to identify bullets made on the same swage die with different lots of jackets. I’ve heard that one can calibrate the Jeunke machine to zero on one lot of jackets, and with the same zero – check a different lot of jackets and obtain a different reading (+/- of the original zero). Can anybody verify this?

Greg Walley
Kelbly’s Inc.
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Greg, this is as close as I can get . . . probably not what you're looking for . . . :eek:

Lou's is an interesting question, and one I've always asked - ok, two questions: 1) what is measured; 2) What is the CALIBRATION standard?

A LONG time ago - too long for me to recall [all of] the details, I submitted a set of bullets, made with varying jacket-wall thicknesses, and different amounts of variation (commonly referred to as "run-out'), to several Juenke enthusiasts. The bullets were bagged, one per baggie, and labeled, "A,B,C, etc. (or, maybe 1,2,3, . . . .) - none of those people could accurately correlate (sort) "readings" to the measured wall-thickness variation. I believe I included several jackets of each incremental variation.

The "run-out" probably ranged from 0.0001" to around 0.0007", as measured ON the J4 production DATUM lines, using a Starrett dial indicator, mounted on a Niemi Engineering jacket "spinner", prior to core-seating. I have NEVER contended that the Juenke machine measures NOTHING, but I do not believe it measures wall-thickness uniformity. My opinion has always been that it measures, "geography" - but, that's just an opinion. My bullets - both BT and FB - have invariably "tested" well on this device - why, I do not know - I suspect good dies.;)

I have been on record as being, and will continue to be mistrustful of any device which has neither calibration STANDARD, nor DEFINED unit of measure: volume; length; weight, etc.:confused: However, I do believe it measures something - perhaps Jerry is , "on to something." RG
 
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Thanks Randy

I say this I only have one machine . Find me another to buy and I'll pay engineers to figure out what it does.
I'm not going to do it to mine.
 
what would a machine 1995 era, be worth at this time?

I've used it to set up bullet dies, 30 cal. i found it came in
as a use full tool for setting up the core seat die. if you got that
right then you were making good bullets. you didn't always need
tons of core seat pressure. big variation on jacket metal.
i've had jackets that were hard to make a bad bullet.
those bullets broke a bunch of Hunter and VFS records.
ken
 
Ken Livengood said:
what would a machine 1995 era, be worth at this time?

I've used it to set up bullet dies, 30 cal. i found it came in
as a use full tool for setting up the core seat die. if you got that
right then you were making good bullets. you didn't always need
tons of core seat pressure. big variation on jacket metal.
i've had jackets that were hard to make a bad bullet.
those bullets broke a bunch of Hunter and VFS records.
ken
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friggin' GOLD right there.... :cool:
 
don't have one, but a guess

Lou Murdica said:
This machine has been around a long time now.
<snip>
We do know it is measuring some thing.
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Based on the inductive probe head, the general description at the website selling kits, and the comment about using it to measure pipe wall thickness, it sounds as if it is measuring sheet resistance (eddy current probe). This is fairly standard in several industries.

If the material being measured is homogenous, then roughly, the sheet resistance will be an indication of how thick it is. If one was measuring a copper (very conductive) jacket over a lead (not very conductive) core, then the sheet resistance could be dominated by variations in copper thickness depending on how deep into the lead core the probe is sampling.

The same would be true for a cartridge case wall, measuring the sheet resistance of the brass over air (not conductive) with variations in case wall thickness changing the sheet resistance and the reading.

If this is true, then running a round homogenous part through the tool should result in minimal deviation since the material and sheet resistance is uniform. Putting different diameter or different material parts would likely change the initial reading requiring re-zeroing, but otherwise they would be stable.

One potential issue is the geometry of the part has to be very uniform relative to the sampling area of the sensor. If you had a perfectly uniform thickness jacket that was elliptical in cross section, you might be able to see deviations because the differences in sampled geometry would give different values.

Greg Walley's experiments I think are inline with this.

1) Varying the core doesn't have much effect because it is not being measured and very small deviations (a scratch or a small pocket) might not show up depending on how much area is being sampled. Example, an indicator probe (ball) would not register the true depth of a scratch because it's relatively large size does not allow it to interact with the scratch.

2) If all you are measuring is the thickness of the copper jacket, then you should be able to distinguish different lots (thicknesses) of jackets with a fixed calibration of the instrument.

The corollary would be that very uniform jackets that have been uniformly swaged should have very little measured deviation...
 
What corolis writes sounds quite reasonable. If this is the result of the measurement there would need to be quite a variation in the sample(s) for a significant deviation in the dial reading. IMO, and if that is so, for where we are in benchrest jacket manufacturing this gadget is probably worthless!!

With Bart's super precision jackets coming on line we are probably way past the utility of Mr. Juenke's instrument.
 
What happens if you spin a Barnes, machined solid copper/zinc bullet. And, what happens if you spin a bullet that has been turned upside down and heated with a torch until all the lead runs out. So you are spinning nothing but the formed jacket.
 
What the I.C.C. unit can do for an accuracy minded shooter

Found on the web...

"What the I.C.C. unit can do for an accuracy minded shooter:

When bench-rest shooting became popular after WW ll, top shooters started testing various makes of bullets to see what was really required to be competitive in the sport. In the .22 and 6mm diameter range, it was decided that a maximum of .0003” in bullet jacket concentricity was the limit in order to shoot competitive small groups in a good bench-rest quality rifle by an experienced shooter. On the I.C.C. unit, .0003” is equal to about 15 deviation units on the meter scale as the bullet rotates. I have tested thousands of top grade custom bench-rest bullets.

The following is average data based on the average lot of bullet jackets that the custom bullet makers can buy. 80 % of the finished bullets will run 5 or less deviation units (Hummer bullets). 15% will run 5 to 10 D.U. (still good bullets). 5% could run 10 to 15 D.U. (average bullets). Anything over 15 D.U. should be used for fire forming, fouling shots, pressure testing, and chronographing. There may not be many of these, but they could cause those small fliers that we all shoot once in a while. Don’t shoot these on match day. Give them to your worst friend!

I want to seriously make a statement that no serious shooter can doubt. The better a shooter can shoot, the more valuable the I.C.C. unit becomes. At 100 or 200 yds., these people can shoot groups that average less than .250”. They do everything right. They have top quality rifles and hand-loads tuned to their rifles. They can judge wind conditions and have good rests and can hold consistently. Even a slightly bad balanced bullet can cause a .250” group to go to a .3”. This could cause a shooter to go to 5 or 10th place in the match. At 600 or 1000 yds., this can be much worse. A lot of shooters test bullet quality by shooting groups. If these groups are good, they have only tested the bullets that they have fired. A bad bullet can come along at any time and really ruin their day at a match. I guarantee my unit will tell a bad bullet from a good one. You should test every bullet that you shoot, then if you get a flier, you can look elsewhere for the cause.

I once tested 1000 custom bullets for a shooter in California. Not one bullet in the 1000 went over 4 D.U.! That bullet maker got a really good lot of jackets on that order.

Vern S. Juenke"
 
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allenn said:
What happens if you spin a Barnes, machined solid copper/zinc bullet. And, what happens if you spin a bullet that has been turned upside down and heated with a torch until all the lead runs out. So you are spinning nothing but the formed jacket.
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I spun some Nosler solid E tips, 180 gr. bt's, they all spun to less than one deviation unit over the entire bullet circumference surfaces including all the way up to the tip ogive surface, better than any of all the custom br copper/lead bullets that I have spun over the last 20 years.

I am not sure how these solid bullets are manufactured but they sure show a very uniform and consistent profile to flux field sensors.
 
Very interesting Don. Maybe I'll have to shoot some of those Nosler and see how they do.
As to the different bullet types. I think it would be hard to draw a conclusion when comparing them until we know exactly what the Juenke machine is measuring.
 
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