Frequently Asked Questions

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1.      What are 0’s, 1’s, 2’s, 3’s, etc.?

2.      How do I prove that sorting ammo by rimfire concentricity has a benefit in my rifle system?

3.      Can a bullet by straightened that is out of round?

4.      How do I setup my gauge?  Where should the indicator contact the bullet?

5.      How and when should I clean the rollers or the indicator tip?

6.      Do the bearings in my gauge need to be lubed?  Should I pull my gauge apart?

7.      Why are some lots of ammo better than others?

8.      Do I need to set the dial indicator to 0.000 when I setup my gauge?

9.      Why did you shoot twenty round groups in your testing?

10.  At what measurement should I keep or cull bullets?

11.  How do I identify loose seated bullets?

12.  How accurate are loosely seated bullets?

13.  Can I reverse the drive arm on my machine?

 

 

 

What are 0’s, 1’s, 2’s, 3’s, etc.?

 

 When we sort ammo we use the following standards:

A bullet is considered a:

If the run-out is between:

0

0.000” and 0.005”

1

0.005” and 0.015”

2

0.015” and 0.025”

3

0.025” and 0.035”

4

0.035” and 0.045”

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How do I prove that sorting ammo by rimfire concentricity has a benefit in my rifle system?

 

The first thing you will need to do is sort some of your ammunition.  You will want to sort enough ammunition so that you have twenty 0’s and twenty 3’s.  Take two targets to the range, preferably on a calm day, and shoot the 0’s on one target and the 3’s on the other.  Score both targets and this should be more than enough to prove the benefit of sorting ammo for your rifle system.

 

Testing and benefits is also dependant on the distance you are shooting.  The benefits in match grade guns at 50 yards or meters is very apparent.  At 100 yards or meters it is a very significant difference.  At 200 yards or meters, it is the difference of night and day.

 

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Can a bullet by straightened that is out of round?

 

The short answer is that we have never been able to make this work.  You can make a bullet appear to be straight using our gauge.  Spin the bullet until the high side is up as seen by the dial indicator.  Tap on the top of the indicator needle that is protruding from the top of the gauge.  This may take a couple of iterations but eventually you will be spinning the bullet and it will appear to have no run-out.  We tried this and then shot them to see if the results were the same as out of the box zeros.  What we learned was that these straightened bullets shot like their original run-out indicated.  In other words if we started with threes and then straightened them, they still produced a group like bullets with three thousandths run-out.

 

What we theorize is happening is that we are straightening the part of the bullet that is outside the case but not affecting the base of the bullet that is crimped inside the case.  Remember we are using bullet run-out to actually give us an indication of the angle of the base of the bullet.  It is the angle of the base of the bullet upon exiting the muzzle that is causing the dispersion that we see at the target.

 

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How do I setup my gauge?  Where should the indicator contact the bullet?

 

You should have the indicator tip positioned one-fourth to half the way down the ogive of the bullet.  This should give a very precise and sensitive reading.  It will also be a much smoother reading than indicating on the knurrled section of the bullet.  This is a good picture of where the indicator tip should be positioned on the bullet.

 

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How and when should I clean the rollers or the indicator tip?

 

Yes is it critical to keep the roller shafts and indicator tip clean while sorting.  Some bullets will have a little lube all the way up on the case and this will transfer to the shafts. These shafts will start to look "dull" when lube is on them.  This needs to be cleaned off periodically while sorting.  I do it when I clean the dial indicator tip.  A cleaning patch with alcohol is more than sufficient to wipe off any buildup.  We are making very precise measurements in a very precise machine.  "Cleanliness is next to Godliness"

 

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Do the bearings in my gauge need to be lubed?  Should I pull my gauge apart?

 

The bearings in the gauge do not need to be lubed.  The shafts are press fit into the bearings and pulling the gauge apart will most likely damage the end of the shafts.  Further the Olympic model gauge is hand tuned to have less than 0.0005” total machine error and pulling the gauge apart and reassembling it will more than likely introduce more machine error, which will affect the accuracy of ammo measurement.  If you feel that you have developed a “rough” feeling bearing, please contact us to evaluate the best course of action.

 

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Why are some lots of ammo better than others?

Our customers are definitely learning that some lots of ammunitions have a better yield of bullet run-outs than others.  This means that some lots may have as many as 10 to 15 percent of the bullets with zero run-out.  Other lots may have as low as 5 percent zeros.  Obviously what we want to buy is the ammo that has the highest percentage of zero run-out bullets.  Several people have told me that what they now do is purchase a brick of several different lot numbers.  After determining the yield of bullet run-outs and which velocity performs best in their rifle system, they then purchase case size quantities of that lot number.

 

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Do I need to set the dial indicator to 0.000 when I setup my gauge?

 

No you do not.  We are only concerned with how much the dial indicator needle moves, not that it starts at zero and moves to three.

 

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Why did you shoot twenty round groups in your testing?

In order to answer this question we first need to define a few terms: 

 

RIFLE SYSTEM: The combination of the rifle and the ammunition as it will be used in competition.

AVERAGE DISPERSION:  A calculated value usually based on averaging several five shot groups.

TOTAL DISPERSION:  The maximum group size that the rifle system produces.

STANDARD DEVIATION:  The statistical measure of spread or variability of the data.

 

The goal of our research was to determine the total dispersion associated with bullet concentricity in a rifle system.  Obviously several steps were taken in order to discover what this total dispersion is.  The testing was performed at an indoor range to eliminate environmental (i.e. wind) influences.  A 2 inch ballistic test barrel was used to minimize harmonics.  A machine rest was used to eliminate human error.   Once all of these controllable factors are addressed we can truly learn what the total dispersion of the rifle system is.  In order to find the total dispersion of the rifle system we need to fire a sufficient number of rounds into a group to prove that all of the bullets are landing within that group and the group size is not getting any bigger.  The data we produced in 2004 at H-S Precision statistically supports our conclusion.  If you look at the group sizes across 80 rounds (4 twenty round groups) for the premium ammo you find that the data is very consistent with a low standard deviation.  Therefore we have found what the total dispersion of the rifle system is by using twenty round groups.

 

Unfortunately what we encounter in publications about rimfire accuracy in the United States is average dispersion.  This number is usually calculated by taking six – 5 shot groups and averaging the group size produced.  A calculation such as this is only valid if there is a high degree of consistency in the group sizes and a very low standard deviation for the data.  An example of where calculating the average dispersion would be valid would be if our six group sizes were 0.27”, 0.29”, 0.30”, 0.28”, 0.29”, 0.28”.  This data would produce and average dispersion of 0.285” plus or minus 0.010”.  The data is consistent and the standard deviation is small.  Granted we still have not learned what the total dispersion of the rifle system is but we do have a good indication of the accuracy of the rifle system supported by consistent data.

 

Let’s work through a real world example.  In a recent accuracy related publication in the United States, the authors were trying to determine the accuracy benefit of having a certain device attached to a rifle.  Six – 5 shot groups were fired with the device attached and the experiment was repeated without the device attached.  The data with the device attached was:  0.480”, 0.505”, 0.505”, 0.575”, 0.400”, 0.260”.  The data without the device was: 0.745”, 0.520”, 0.540”, 0.450”, 0.345”, 0.400”.  When we calculate the average group size for each with the standard deviation it is: attached – 0.454” plus or minus 0.111”  no device – 0.496” plus or minus 0.133”.  We can all see the obvious conclusion that the groups with the device averaged 0.042” smaller.   When we realize that the standard deviation of the data was 3 times this number we know we haven’t produced any consistent data though which we can make a genuine conclusion.  Obviously we are not making the statement that this device does not improve rimfire accuracy.  We are concluding that the data presented in this article does not statistically prove the benefit of using this device.

 

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At what measurement should I keep or cull bullets?

Our research discovered the following formula: for every 0.001” in bullet run-out, group diameter increases 0.1” at 50 meters.  This question has no straight forward answer, because it depends somewhat on the shooters abilities and expectations.  However, we believe that almost everyone should cull bullets with between 0.003” and 0.005” run-out because these could easily cost you points.  If you are a competitor going to an Olympic Finals match, you probably only want to be shooting bullets with 0.000” run-out.

 

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How do I identify loosely seated bullets?

 

When measuring a normal bullet in the machine, the indicator needle will swing smoothly from a high to low reading.  When measuring a loose seated bullet you will see the dial indicator needle jump back to a lower number.  Some loosely seated bullets appear to make the needle vibrate as it swings.  Quickly being able to identify loosely seated bullets can only be learned with experience.  These hints should get you started correctly.

 

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How accurate are loosely seated bullets?

 

Our research provided proof that loosely seated bullets shoot nearly as well as hard seated bullets with zero run-out.  The only plausible theory at this time is that loosely seated bullets self center as they are chambered in the rifling of match grade guns.  In simple terms the order of accuracy that was proven in our research was 0.000 < loose seated < 0.001 < 0.002 < 0.003 < 0.004 . . . etc.

 

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Can I reverse the drive arm on my machine?

 

The Olympic Model is not reversible.  Never disassemble this model.  In the final assembly process, run-out error is indexed, offset and then pressed together.  This process eliminates error in the machine.  The new Club Model is made to reverse the drive arm to either left or right hand, please see instructions.

 

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