Just received my digital hornady caliper. two gauges diff readings

[Bytesniffer]

I bought another digital gauge
To verify my readings
My new hornady gauge
Read cartridge length
1 thousandth to 1.5 thousandths
Smaller then my ez calc I've
Had for 6 months.
Head space gauge with hormady caliper reads
Almost 5 thousandths smaller

Which ones right ?

[JeepHammer]

Do you mean 'Digital Caliper' instead of gauge?

There is something called 'Standards'.
They are SPECIFICALLY GROUND PRECISELY to test your calipers, micrometers, etc.

The last number in part number is length, 1", 2", etc
Since body heat can make the standard expand, these are insulated.

http://www.starrett.com/metrology/me...&sortBy=wp/asp

[JeepHammer]

The idea is...
ZERO your caliper/micrometer, whatever with jaws/anvils closed.

Then measure this thing, it will tell you if the SCALE is accurate, since these are ground to VERY precise length.

It bothers me the discription says 'Spherical' ends and shows flat ends...

Someone else can direct you to their favorite sites/types...

-----
Standards get used for NOTHING ELSE !!!
Find a soft, protected spot for them, this is the ONLY use!

If you don't put them away, they rust, some idiot uses them as a punch, they fall onto hard surfaces etc.
This is the 'FIRST WORD', the ones that tell you your measuring equipment is accurate & correct.
First step in getting ANY ACCURATE READING of any kind.

Better digital calipers & micrometers come with standards, which immediately get lost when you don't know what they are & what they do.
'Lesser' devices don't ship with standards because they will show up flaws.

[Bytesniffer]

Yes I m sorry
It a hormady digital caliper.
The jaws are a little loose
And move up and down slightly.
My other caliper is very rigid
And don't move.
Its constantly off by .5
And 1 thousandth
When I close up to check if
Zero as im measuring .
Think its the problem
Need to send back.

[HiBC]

I suggest becoming a bit more realistic with your expectations.
Hornady does not make calipers.They buy import lo-buck calipers,then resell them to you.What,$29? Its a mediocre Chinese "bargain" tool.

IF you know what you are doing,SOME improvement might be made adjusting screws. And,of course,poke the zero or cal button with the jaws CLEAN and closed.

You can do useful reloading work with cheap calipers.Trim case,set seating depth,etc.

If you want a tool that will ballpark .001, look to Browne and Sharpe,Tesa,Starret,Mititoyo,ets. Etalon is good.

For a loading bench caliper I use OLD SCHOOL vernier scale calipers,used,off e-bay.No dial,no rack,no batteries,no digital.

Any of the brands mentioned,plus Helios,Mausers,Fowler...A few more.SPI.
You want satin chrome,not shiny.

CalipersCAN be pretty accurate,many are good to .001. But if you NEED .001,Calipers are the wrong tool.

[Reloadron]

OK, here is what I suggest, again. Buy yourself a Headspace Gauge. Now just so we are clear about this, back to the SAAMI glossary of terms:
HEADSPACE
The distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats.
HEADSPACE GAGE
A device used in a firearm to determine the distance between the breech face and the chamber surface on which the cartridge seats. Also called Breeching Plug.
Just so we understand each other lets work from industry standard definitions.

This is an example of a SAAMI Cartridge and Chamer drawing for the 308 Winchester cartridge and chamber. It is marked up.


These are Headspace Gauges. They can be purchased singular or as a set. I suggest you buy one, you only need one. If you want to compare the accuracy of your Hornady gauge set you use a known value. A simple 308 Winchester Go headspace gauge will be 1.630".


We covered all of this before. Here is the example. The known gauge is a 1.630" headspace gauge and the vernier reads 1.624 telling me the Hornady gauge reads low by 0.006". The Hornady gauge is designed to be used for comparison only. The numbers you get, as can be plainly seen are not true dimensional numbers.



A 308 Winchester Headspace Go Gauge should run you about $35 to $40 and will tell you exactly how much your Hornady gauge set is off.

Here, $28.99 from Brownells.

Ron

[JeepHammer]

When you check calipers with a standard, check deep in the jaw, then shallow in the jaw (and maybe in the middle also).
That will tell you if the jaw is loose, or your jaws aren't adjusted square to each other.

Guys argue that calipers are all the same, but there is a HUGE difference between manufacturers/brands.
Every starter in about every machine shop starts with 'Harbor Freight' (or similar) low budget calipers,
After screwing up fine detail/high tolerance jobs they get a high quality unit.

------

Keep in mind you have to be realistic when bending brass.

The likelihood you are going to get EVERY brass to a specific size is ZERO.
NO ONE, NOT ONE SINGLE PERSON gets every brass EXACTLY where they want it.

You have seen the posts on guys using feeler gauges, changing lube, tapping the die, annealing... doing everything under the sun to squeeze that last 0.002" or 0.001" out of a stubborn case...

The easiest way to prove this to yourself is get a box of brand new, big brand name rounds and use your compairator adapter on them right out of the box...
Bottle neck cases are a PAIN even when you have millions in presses...

Set REALISTIC goals,
Use ACCURATE measuring tools,
And keep asking! The internet community will give you ideas from ragingly stupid to so slick you won't believe it works so well...

Once the 'Precision' bug bites, it's REAL hard to get rid of.
You will be frustrated A LOT, but you will figure out what works for you,
And the more you do it, you will figure out what makes a difference in accuracy when fired and what just isn't that big a deal...

[JeepHammer]

Ron,
I DO NOT DISAGREE with anything you posted.

However...
Your 'Standard', The Headspace Gauge, how do you KNOW it's exactly the correct length?
Since you are using that gauge as an 'ABSLOUTE STANDARD', how do you determine it is accurate from the manufacturer, and hasn't worn or been damaged?

There is a reason I start with standards from a reputable manufacturer and keep them sacred.
There is a reason I start with a ACCURATE measuring tool that has been checked against standards.

I own headspace 'Go/NoGo' gauges & standards, I WOULDN'T chamber firearms without them...
The point I'm trying to make, without at least ONE Datum Line adapter WITHOUT taper, the hole PERCISELY 0.400" & Square Edged,
There is no way to check your headspace gauge/standard.

AND,
If I'm going to use a square edged adapter with a 0.400" hole to check the chamber gauge plug,
Then I'm simply going to use that 0.400" adapter since it's a direct & ABSLOUTE reading.

Normally, ZERO on target Datum Line measurement, and let my caliper tell me +/- instead of absloute read every case...

I have screwed up too may things giving blind faith to 'Standards' and 'Gauges' someone else made...

[Reloadron]

Hey Jeep, real good question.How do I know my standard is true?
Before I retired several years ago, actually will be 4 years in May, I had access to some great stuff including a standards lab. I dragged in all my mechanical gauging and had my lab guys and layout guys run them. I had all my stuff calibrated. I worked in a sort of skunk works for Navy Nuclear Propulsion and DoE. The gauges were run on a Zeiss CMM which I trusted.

Life was actually good as I had full access to a real nice proto type machine shop as well as standards lab. I was fortunate to work with some of the best ME types in the country. I worked on the electrical side of things.

Anyway that was a real good question as to how do I know what my gauges say is true or a good level of legal truth. Calibration with comparison to a higher level standard. The job was a great career but I am now happy to be retired and glad I went out at 63. The wife was two years older than me and she retired also.

Finally on the bright side with good care and treatment my mechanical gauging is not likely to change. If I have any doubt I still have friends at the plant.

Ron

[Bytesniffer]

I'm misleading you guys again,
It does measure good.

The issues I have is when I
Put it down on the towel I'm
Measuring on, the scale changes
To a thousandth off.
Also, as I checking the headspace
Or measuring the length of
Some rounds , I keep finding
Its off and need to zero it
A lot .
I think its because the jaws are
A little loose.
That's way I'll just return it.

[F. Guffey]

I bought another digital gauge
To verify my readings
My new hornady gauge
Read cartridge length
1 thousandth to 1.5 thousandths
Smaller then my ez calc I've
Had for 6 months.
Head space gauge with hormady caliper reads
Almost 5 thousandths smaller

Which ones right ?

I am sure there is another tool out there somewhere that some reloader believes you should have, I don't. I am the fan of verifying, I am the fan of transfers, I am the fan of standards (if I do not have a standard I make it). I believe you should learn to zero your gages. For many years I thought reloaders believed gages were made on Mars and never considered gages are made by people.

I would suggest you learn to zero your tools or use them as thought they were comparators. One of my favorite tools is the feeler gage, it is a standard and transfer.

F. Guffey

[F. Guffey]

I'm misleading you guys again,
It does measure good.

The issues I have is when I
Put it down on the towel I'm
Measuring on, the scale changes
To a thousandth off.
Also, as I checking the headspace
Or measuring the length of
Some rounds , I keep finding
Its off and need to zero it
A lot .
I think its because the jaws are
A little loose.
That's way I'll just return it.

Not me; and then there is the case and head space, in the glossary of terms it is said many reloaders are confused about it. The case does not have head space. Most of the confusion comes from my use of the length of the case from the shoulder to the case head. I off set the length of the chamber with the length of the case from the shoulder of the case to the case head.

Most are confused? Some reloaders have SAAMI on speed dial. SAAMI does not list head space for the case; I suggest reloaders speak where SAAMI speaks and be silent where SAAMI is silent.

F. Guffey

[NoSecondBest]

Calipers need to have the jaws cleaned and zeroed before use. Zeroing is really, really easy. If they're off, they are easy to reset. Laying your calipers down on a towel and seeing a .001 change isn't any big deal. What a lot of people don't seem to realize is that the last decimal is a close approximation to what is actually being read. Let me explain: If you need to read something to three decimal places you need a four decimal place gage. Why? If you're reading let's say 1.175" the part measured might actually be 1.1759 inches. You're just seeing the first three places. You don't know if you're getting 1.1759" or 1.1751". Either number is closer to the next higher or next lower place. The fourth decimal is called the discriminating decimal. It allows you to accurately determine the measurement closer to three decimal places. If you want/need to know the third decimal place you need a gage that reads to four places. You need to zero at each session, and you need to wipe the jaws off with a clean cloth each time. You also need a cal block to check accuracy. For your needs, one cal block at at 2" might be all you need.

[JeepHammer]

Clean & Zero both calipers.

Measure something solid, Anything you have laying around that is 'Flat'.
Feeler gauges and plate glass come to mind right away...

Do you get the same reading from both?

This is the old 'Two Levels' test,
Lay two levels back to back, if the read the same they are both 'Right',
This is because the odds/chances of having two levels off exactly the same in opposite directions is virtually none.

The next test is done the same with something thicker.
Check ZERO, check around 3/8", check again about 2" long.
If both calipers agree, both are *Probably* fairly accurate on scale.

ABSLOUTE testing takes an absloute standard (gauge) of known length.

A pair of calipers *Can* be the same amount 'Off' and both lie, but the odds are slim.
This DOES NOT certify the 'Absloute' reading, but it verifies the scale on both units is somewhat CONSISTANT and reading properly.

Calipers shouldn't have 'Loose' jaws.
They should hold a reading on their own, but all bets are off when you lay one down...
Use the thumb screw lock if you want to retain a reading when you lay one down.

By the way, laying your calipers on a towel is a VERY good idea!
Most of us don't take care of measuring equipment like we should.
The scratches on the backs of my equipment testifies that I'm guilty...

[Aguila Blanca]

I tried a digital caliper once. I hated it -- it ate batteries for breakfast, lunch, and dinner. I've reverted to using dial calipers. I know how to read them, they don't use batteries, and they're easy to zero if the temperature in my basement changes (which is rare).

[F. Guffey]

Aguila Blanca, and then there are those adap-ter-kits that are added to the dial caliper, basically that is the cause of most of the confusion, reloaders believe because they close the caliper and then adjust to zero the tool is zeroed.

I use the Wilson case gage as an example of a datum based tool and then everyone gets all choked up because they are confused. Anyhow, I make datum based tools, to zero is an automatic, I close the tool and there it is. L.E. Wilson has made tools that way close to 60 years, and after all these years reloaders continue to call the Wilson case gage a drop in gage. The big offender is a tool manufacturer that wants reloaders to purchases his tool; he calls his tool a head space gage and to me his tool looks exactly like a comparator.

F. Guffey

[NoSecondBest]

reloaders believe because they close the caliper and then adjust to zero the tool is zeroed.

Oddly enough, I believed it also. I worked as an engineer and managed a metrology lab and that's what we did. You are supposed to clean and close and set to zero. The problems come after that if the gage is damaged or worn. That almost never happens. In several years I'd only put a couple of sets out of the system for gage error or accuracy. All my labs were certified and we had thousands of gages in the system.

[bedlamite]

Here's the inside of Chinese calipers. NSFW language:

https://www.youtube.com/watch?v=WvszAb0Y0Ec

[T. O'Heir]

"...The jaws are a little loose..." That's your issue. No need for headspace gauges or anything else like 'em. Headspace gauges are for checking tolerance on rifles. Not case lengths.
Yes, calipres absolutely need to be zeroed. Easiest to use, least expensive, tool to do that is a set of feeler gauges(Used for setting spark plug gaps.). Gives you a flat, precision tool of a known dimension. Feeler gauges can be had in any hardware/automotive supply shop.
Mind you, a factory jacketed bullet will do the same job.

[Reloadron]

NoSecondBest:

Oddly enough, I believed it also. I worked as an engineer and managed a metrology lab and that's what we did.

Metrology lab? So you were a weatherman? Why would a weatherman need or use a vernier caliper.

Seriously, I do know the difference between Metrology (The Science of Measurment Technology) and Meteorology (The Science Dealing With the Atmosphere and its Phenomena, Including Weather) but I just could not let the reference to Metrology pass. I also agree.

Ron

[HiBC]

This is rather interesting.
The gentleman who suggested starting with a headspace "go" gage is,IMO,the most correct.
If you feel the need to verify the calibration of the hardened and ground steel gage,OK.Not wrong.

But that done,its a repeatable standard to go back to what a minimum SAAMI chamber should be cut to. In other words,it represents a standard to size ammo to that will fit in ANY SAAMI spec chamber..
Now the handloader can set his tool to that baseline,and THEN,from his notes,decide I want plus .003 for THIS rifle.

The idea that any aluminum bushing with less than razor sharp corner clamped to a caliper can more accurately represent a standard than a hardened and ground gage is amusing.
You certainly CAN set your Hornady bushing on the headspace gage,hit "zero" and then measure an approx. + or - from there.

I have made a lot of military,aerospace,and other high precision parts.
There are different levels of precision,but generally calipers and micrometers are .."navigation"tools for the machinist.

Often,they are not acceptable to qualify a part. Holes get accepted/rejected with a calibrated plug gage.Rounds are qualified good/bad with a ring gage.

There is a device called a "comparator" that is a stand with a very flat stage.A very sensitive indicator is attached to the stand,often graduated in 50 millionths of an inch. You set the gage with carbide Johannsen blocks,traceable to the Bureau of Standards.
And,dial bore gauges,etc are calibrated to a Johannsen block set to zero for each job,the indicator showing + or - in to 50 millionths.

Point,the yes or no qualifying standard is a a gage,

Now,with all due respect for a feeler gage,how flat/straight is it?

I have,on my loading bench,a flat of black granite with a post on it and a clamp for a dial indicator. If I take my Wilson case gage and stand it on the granite, I can set my dial indicator zero on the min or max step of the gage,and the little limit flags on the indicator dial face to whatever tolerance I want from there.
I can drop the brass in the Wilson gage and pass it under the indicator to get a read for,example -.003 from max length or actually +.003 to reduce head clearance for a particular rifle.

Its just another way.

Mic setting standards are OK,I always used Jo blocks

A pretty good bargain for a decent set of "standard" blocks to use in a shop isa set of "space blocks". they are about 3/4 in in dia,round,with a threaded hole in the middle.They are steel,hardened and ground.
I think maybe $50or $60 will buy a set.
You get a set that can be stacked..like .101,.102,103,etc.THen .110,120,130 And a .050,a.0625,
A .100,.200,.300,a.500,a 1 in,a 2.00 in,etc. You can stack them on an allen set screw.Use them with lathe and quill stops,sine bars,measuring slots,etc.

[F. Guffey]

Hey Jeep, real good question.How do I know my standard is true?

I have said there is something about the datum reloaders do not understand. I have also said there is something about the head space gage a reloaders does not understand. I have also said there is something about gages and micrometers the reloader does not understand. I have said I make datums, and I collet datums and there are times I purchase datums; Bascialy I am told there is no such thing as 2 datums; it would seems I am the only reloaders that understands the plural of datums.

Anyhow, a reloader with a dial caliber that has the shop skills to zero their dial caliper has the ability to measure the length of a head space gage from the datum to the head of the gage if they have the ability to make a datum.

At the end of last month I had the opportunity to purchase 200 pounds of datum makers, instead of the datum makes I purchases a cabinet and 3 Binks pressurized paint cans for $25.00 each. If I go back to purchases the tools I will need the cabinet; it is one of those 22 drawer file cabinets.

F. Guffey

[condor bravo]

To try to determine which caliper is closer to being right, do something simple like measuring a bullet diameter. If you have access to Sierra 168 gr .30 caliber Internationals, now called Matchkings, they should measure right on at .308. My recent acquisition from Harbor Freight measures exactly that while a more expensive set I had dropped was a good .001 off. Or try other .30 caliber bullets, whatever you have.

[Unclenick]

The plural of datum is data. You hear people say they took a single data point, but they actually mean they recorded a datum.

[F. Guffey]

The plural of datum is data. You hear people say they took a single data point, but they actually mean they recorded a datum.

True, I hear that all the time and then say to my self; "if they are not careful they are going to talk it to death". I can not take a single point data because I measure from and to meaning I have to measure from two points.

Datums: Datums make it possible to find one of the points. In the big inning I saw the same thing everyone else saw; the difference? I was not the one that was confused. In the big inning smiths and reloaders found a drawing of a case that was supposed to explain everything. Everyone recognized the drawing of the case but there was a line drawn through the shoulder with an arrow that identified the line as a datum line and an explanation. The explanation gave the rational; "and that is how they do it". Do WHAT! ? From that day on reloaders used up a lot of space on the Internet talking about 'the lline'. You will not believe how difficult it was to convince reloaders the line was a round hole/circle.

So, I made datums, I made circle/round holes, to verify a head space gage I select the correct datum/round hole, If I have two .375: round holes I have two datums for the 30/06 family of cases that will also work on the 300 H&H.

Again, L.E. Wilson had this figured out in the early 50s, when a case is placed into a Wilson case gage the case sits in the datum of the case gage. One more time, the Wilson case gage datum has a radius but when Wilson is grinding the case gage to length; how can they miss?

Because this stuff does not lock me up I used a straight edge and a feeler gage, I have found a flat surface works better; problem, reloader believe I am doing a magic trick like turning nickels into times.

Again, I make datums, I collect datums and when I can sneak up on someone I purchase datums. And then there are tools that are used to make datums. When I mess up and my datums do not work out I turn them into comparators.

Hey Jeep, real good question. How do I know my standard is true?

You need to find someone that can teach you how to zero your gage.

F. Guffey