Resizing discrepancy! Wilson gauge vs Hornady bushing

[207Shooter]

First off I’d like to thank you guys in this forum for the wealth of information I’ve been able to learn searching this forum.

Reaching out to you guys because I just can’t seem to make heads or tails of the numbers I’m getting. I’ve been using the Hornady bushing to measure shoulder bump since I started reloading around 2 years ago. Seemed to work alright for me so far. That is until I broke out my Wilson micrometer head yesterday. Initially I just wanted to play with the Wilson gauge (which I forgot I purchased a year ago) and to verify that my shoulder bump was matching what the Hornady bushing was showing. I was resizing 223 and set the RCBS FL sizer to bump the shoulders 0.004”. On each case I checked with the Wilson gauge I was getting 7-8 thousands shoulder bump. Kind of a headscratcher but since I was just loading some plinking 223 with mixed headstamp brass I didn’t give much though to it.


Fast forward to today and I’m sizing my 9x fired Hornady 6.5 Creedmoor brass. My die had been setup to bump the shoulders 0.002” when measuring with the Hornady .400 bushing with no real issue in the past. But when I started sizing today I pulled out the Wilson micrometer head again to see if I could get it to confirm the measurements taken via the bushing. The Wilson gauge was very repeatable, showing 0.006” shoulder bump. I got on the phone with Wilson in the hopes that I may have been missing something obvious and didn’t come up with anything. So, I backed the sizing die out until the Wilson gauge showed I was bumping the shoulder back a very repeatable 2 thousands. These rounds chambered in my rifle just fine. The problem is when I size 0.002” based off the Wilson gauge reading my brass grows by 0.002” from the fired state according to the Hornady bushing. I tried swapping the .400 bushing with the .375 bushing with the same results, I’ve got a good set of Mitutoyo calipers & I’m conscious and try to be consistent on how much pressure I’m putting on the caliper jaws. So I’m left trying to make sense of what’s going on.


Any help will be appreciated!

 

[Otto]

The 375 bushing is what Hornady says to use for 6.5 Creedmoor.

 

[207Shooter]

The 375 bushing is what Hornady says to use for 6.5 Creedmoor.

Agreed. Whether your using the 400 or 375 it still sits on the shoulder and compares measurements. Still doesn't explain the discrepancy between the Wilson and Hornady bushing's measurements

 

[Blue68f100]

Do you have a set of Go/NoGo gauges, you can use them to check zero.

Hornady is more of a comparator not an actual gauge. So you actually use it before and after to see the change .

 

[Reloadron]

No clue why Hornady would suggest the .375 when the 6.5 Creedmoore cartridge measures from the case head to the o.400 datum point on the shoulder. The minimum and maximum are Min 1.541" and Max 1.551".

Next the Hornady gauge is used as a comparator and that is as good as it gets. It will not give you the above numbers or at least I have never found one that does. Most new ammunition will come in right around the Min of 1.541". The idea being fire a cartridge. Take a measurement. Size down a little and take a measurement. Once you are about 0.002" less than where you started the resized cartridges should easily chamber in the rifle they were fired in. Just remember you are comparing before and after thus a comparator. Here are a few examples using the Hornady:

Set the gauge up and zero it:


Next I insert a known .308 Winchester Go gauge, actual headspace gauge.


The gauge is a known 1.630" headspace gauge yet I get 1.624" or actually 0.006" low.

Next I measure a No/Go gauge which is 1.634".


So while the Hornady gauge did as advertised, it reflects a delta of 0.004" which is correct the numbers are not close to the true actual numbers. The 308 Winchester cartridge measures from case head to the datum point where the shoulder crosses a 0.400" datum point. The 6.5 Creedmoore uses the same datum. The problem is if you look at the corner breaks on the Hornady bushings they have a slight radius and are not sharp corner breaks. If you look real close maybe under a little magnification the radius chamfer is apparent. The reality is be it a 0.375" or 0.400" bushing it will not be true and it will not give an accurate real world number but a number suitable for comparison.

Now to the Wilson gauge. When you drop a case in the gauge and the case head is absolutely flush with the lower step you can figure that cartridge in the case of a 6.5 Creedmoore is 1.541" and the upper step is 0.005" above that or 1.546". The image is not a Wilson but same type gauge.



The idea is the Wilson gauge is reamed like a chamber and the inserted cartridge headspaces like it would in a chamber. So following the destructions err rather instructions:


Notes:

• This is a one-piece, non-adjustable cylinder-type gauge for checking fired and resized cartridge cases for cone-to-head and overall length
• Used to compare cartridges against the minimum and maximum SAAMI cartridge dimensions
• The item description will indicate if the headspace gauge is Adjustable

Instructions:

• Drop a fired case into the gauge. Take a measurement on headspace. This can be done with either a depth micrometer or caliper (Depending on if the case is sitting high or low in the gauge). If the case sticks out past maximum headspace the firearm probably has a larger than average chamber. The gauge can still be used because it is being used to determine how much resizing is required.
• Now once the initial measurement is taken, slowly dial in the full length sizer until there is a 0.001 to 0.002 drop in headspace. This will give the measurement to resize the case just below the chambers headspace in the firearm being reloaded for, giving a more accurate shot and saving brass by not causing it to be overworked.
• Once the brass has been sized, set the brass in the gauge and set the gauge on a flat surface with the head side facing down. Now look across the top of the gauge, this give the maximum and minimum for trim length.

We can see how the two gauges will likely not produce the same numbers. If you want real numbers I have more faith in the Wilson used with a quality caliper than the Hornady. My first choice is an RCBS Precision Mic for the 6.5 Creedmoore. The Hornady while it does what it is supposed to do is never to likely agree with any other gauge. In the above image if I drop a .308 actual headspace gauge in the gauge my gauge heads are perfect flush.

Additionally more info on Case Gauges can be found here going back a few years. I used some of the same images.

Ron

 

[207Shooter]

I believe you guys may have misunderstood me or perhaps I didn't clearly explain what I was trying to convey.

I attached a photo of the Wilson micrometer head so you guys could get a better idea as to what it does (incase you haven't seen it before). The micrometer head is an accessory to the case gauges that acts as a comparator

I'm well aware that the Hornady bushing are just used as a comparison measurement from fired to sized brass, all I'm using is the delta. I was taking a before and after measurement of my brass during sizing with the Hornady bushing insert. That's where I was initially getting a .002" shoulder bump, according to my calipers. The issue I'm having is when I tried to verify that shoulder bump with my LE Wilson case gauge and micrometer head, which is nothing more than a comparator itself, it was showing .006" shoulder bump, when compared to the same fired case in the same gauge before firing.

THEN, just to see what would happen I adjusted my die so that the WILSON gauge would show .002" shoulder bump, when I checked the same case with the Hornady comparator before and after sizing it showed it grew by 0.002"

The only reason i switched around the bushing's was to see if the discrepancy carried over to the other bushing (effectively eliminating the bushing being the issue).

I guess what I'm trying to say is the delta should be the delta no matter which comparator I'm using. But in my case it's not. I'm inclined to believe the Wilson because my .002 bump in the Wilson still chambers in my rifle.

 

[Walkalong]

I guess what I'm trying to say is the delta should be the delta no matter which comparator I'm using.

Not necessarily.

Believe your Wilson set up.

 

[JFrank]

What's a Delta?
Maybe im in the minority but I don't understand why you don't just use the basic Wilson case gage with the .005 cut out?
They work great

 

[Jim Watson]

I guess what I'm trying to say is the delta should be the delta no matter which comparator I'm using. But in my case it's not.

Consumer grade equipment, consumer grade accuracy.

I'm inclined to believe the Wilson because my .002 bump in the Wilson still chambers in my rifle.

Me, too.

 

[NMexJim]

I don’t have a Wilson set like yours (nice tool) but I’ve used a ton of Starret inside and outside micrometers to 64” (we’re talking two men required) over the years. We kept a set of standards so we could check/adjust all types of micrometers to a zero. Gotta have a zero method/tool. Drop the Wilson once, and you’ll need to able to reset or send it in. Check your Wilson instructions and see if they tell you how or what to use for zero.

Price alone should tell you something about the two, but not all of us are going to spend that amount when a Hornady will work fine.

I also think using two different devices made by different manufacturers is a good way to go coconuts without a standard or way to zero them to each other. Blue68 said it above. I think you use one or the other until you figure out the zero.

 

[Reloadron]

What's a Delta?
Maybe im in the minority but I don't understand why you don't just use the basic Wilson case gage with the .005 cut out?
They work great

The "delta" is the difference.as used in this case. Measure before get a number, measure after and get a number. Subtract the after from before and the number you get is the delta or difference.

Ron

 

[JFrank]

The "delta" is the difference.as used in this case. Measure before get a number, measure after and get a number. Subtract the after from before and the number you get is the delta or difference.

Ron

Is that really a thing ?

 

[JFrank]

Agreed. Whether your using the 400 or 375 it still sits on the shoulder and compares measurements. Still doesn't explain the discrepancy between the Wilson and Hornady bushing's measurements

Were you by any chance bumping a case that had not been fully fire formed than using that as a standard to judge from ?
Asking for a friend......

 

[207Shooter]

We kept a set of standards so we could check/adjust all types of micrometers to a zero. Gotta have a zero method/tool. Drop the Wilson once, and you’ll need to able to reset or send it in. Check your Wilson instructions and see if they tell you how or what to use for zero.
.

The Wilson comes with a zero gauge block. It zero off that gauge at .100" from the factory. (at 75 degrees F) allowing for measurements in both directions.

 

[207Shooter]

Were you by any chance bumping a case that had not been fully fire formed than using that as a standard to judge from ?
Asking for a friend......

They seem to all be fully fired formed and measuring roughly the same with the Hornady comparators across the hole lot. Before I'd size each case I'd first check with the Hornady, write that number down, then with the Wilson & write that number down. Then I'd size the case and check the case again with the Hornady and Wilson gauges. The Hornady would show that the shoulder got bumped .002" and the Wilson .005", since I'm loading for a precision bolt gun that was unacceptable. So I turned the die out to make it so the Wilson gauge would show .002" shoulder bump (since I trust it more). When checked with the Hornady Bushing gauge it was showing that not only was it not reading the same difference (delta) it was showing that it grew .002". And I mean repeatedly over 50 cases.

 

[JFrank]

I use a Hornday type of comparator on my LR bolt guns as well, they have a fairly Sharpe bushing edge to gage with rather then a shouldered gage ( I have encountered shouldered gages with fundamental differences that drove me nuts ) although I go my own path regarding size of bushing.
Example: a 300 bushing for a 6 BR case
Example: base to 300 datum
My measurements are not taken to close to the shoulder.
Added; I always ensure full case growth prior to setting back ( bolt resistance is a good indicator)

Check out a LR tuning thread on rifle country page, im working with new brass now.

 

[entropy]

When in doubt, the ultimate gauge is the chamber of the rifle they will be shot in.

 

[JFrank]

When in doubt, the ultimate gauge is the chamber of the rifle they will be shot in.

This is exactly right, reamers are plus or minus as well as tools they don't always match perfectly, a slight difference at the neck shoulder junction will make ya crazy

 

[Walkalong]

Just use the Wilson and be happy.

 

[garandsrus]

If the round with the shoulder bumped back less chambers fine, go with that!

My only guess as to why you have a difference is that the two gauges are contacting a different part of the case. One might be measuring closer to the neck/shoulder transition and the other lower on the shoulder for the other. When you are minimally sizing, the case neck/shoulder area probably isn't sized the full length which would throw a measurement off if your gauge touched the unsized neck portion of the case. In other words, if you push the shoulder back farther, more case neck is sized.

 

[NMexJim]

The Wilson comes with a zero gauge block. It zero off that gauge at .100" from the factory. (at 75 degrees F) allowing for measurements in both directions.

Then, there you are! You've got a finely made tool that is adjustable to zero. What more could be asked for? Go forward with joy and gladness in your heart! Send the Hornady Comparator by fastest mail to me, and go coconuts no more.

 

[207Shooter]

If the round with the shoulder bumped back less chambers fine, go with that!

My only guess as to why you have a difference is that the two gauges are contacting a different part of the case. One might be measuring closer to the neck/shoulder transition and the other lower on the shoulder for the other. When you are minimally sizing, the case neck/shoulder area probably isn't sized the full length which would throw a measurement off if your gauge touched the unsized neck portion of the case. In other words, if you push the shoulder back farther, more case neck is sized.

Agreed, this is what I've come to accept as well. It's really the only thing that could explain this. Even though it bothers my engineer mind how the numbers don't jive, I'll switch to using my Wilson gauge from here on out.

 

[Walkalong]

My only guess as to why you have a difference is that the two gauges are contacting a different part of the case.

Yep

I'll switch to using my Wilson gauge from here on out.

I see nothing but happiness in your future

 

[Reloadron]

Is that really a thing ?

Would I kid about something like that? The use of the word depending on the context it is used in can have several meanings. One definition for mathematics is : an increment of a variable —symbol Δ. A delta pressure sensor for example gives the user the difference between to pressures. Measure a case and get a number. Apply some sizing. Measure again. The difference is the delta.

When measurements are taken they need to be taken using the same method and procedure.

If the round with the shoulder bumped back less chambers fine, go with that!

My only guess as to why you have a difference is that the two gauges are contacting a different part of the case. One might be measuring closer to the neck/shoulder transition and the other lower on the shoulder for the other. When you are minimally sizing, the case neck/shoulder area probably isn't sized the full length which would throw a measurement off if your gauge touched the unsized neck portion of the case. In other words, if you push the shoulder back farther, more case neck is sized.

That would be my guess. You are measuring from cartridge base to a datum point on the cartridge shoulder and unless the datums are the same point you will get different numbers using different gauges.

Ron

 

[NMexJim]

So, 207, you probably know there are 4 styles or personality types: Amiable, Analytical, Expressive, and Driver. Each of these main headings is also divided into the same quadrants. So, you can an Analytical/Amiable or Amiable/Driver (no such animal), or an Expressive/Driver, etc. It's good to have some versatility. I Knight you an Analytical/Analytical (that's called being jammed into the corner) and the Lord help those that come into contact with you!