Hornady Case Comparator

Rick

Moderator
Staff member
Measures seating depth of loaded ammunition from the bullet ogive to the case head of the loaded round, to eliminate variation in seating depth. Attaches to a caliper.
 

Brad

Benevolent Overlord and site owner
Staff member
If you mean the headspace gauge it is pretty simple.
Bottleneck cases are setup for headspace at a specific diameter on the shoulder. The gauge has a set of gauges which clamp on a jaw of your caliper with a hole of the specofic diameter for headspace on a family of cases-06, 308, mag, etc.

Without sizing deprive a case. Place neck, making sure it is clean first, in proper gauge. Measure length from datum line to head. That is the headspace dimension for the gun brass was fired in.

We can now size the case and adjust the die until that headspace dimension is decreased by say .001. We know the shoulder was pushed back that exact amount.

Not very expensive but very handy.
 

Rick

Moderator
Staff member
If you mean the headspace gauge it is pretty simple.

Nope . . . The headspace gauge and the comparator are two different tools. The comparator measures the seating depth of a loaded round from the ogive to the case head. As opposed to measuring from the bullet tip which can be highly variable.
 

Brad

Benevolent Overlord and site owner
Staff member
I suppose we should ask which tool he is speaking of?
There is an OAL gauge and a headspace gauge.
Neither is called a case comparator on the Hornady website.

Both are very handy and I wouldn't be without either one.
 

Rick

Moderator
Staff member
Insert mounts on caliper jaw with a set screw. I.D. of insert is proper diameter for measuring from the datum line on the ogive to set precise seating depth. My opinion is that it is pretty much a waste of time on the average off the shelf rifle. On bench rest gun? Probably would pay off. The average hunting rifle would never know the difference.
 

Rick

Moderator
Staff member
The seating depth comparator is basically the same thing except it measures from the datum line and not case shoulder.

Whichever he meant he now has info on both. :)
 

fiver

Well-Known Member
I only use the one Rick is talking about.
I want to know how far out my bullet ogive is from the case's base.
 

waco

Springfield, Oregon
The head space gauge is very handy for not overworking your rifle brass. You can very precisely bump the shoulder back .001” at a time until it chambers freely.
 

popper

Well-Known Member
My opinion is that it is pretty much a waste of time on the average off the shelf rifle For seating depth I use a washer and cheap depth gauge, make a dummy round and set the seating die from the dummy for each batch loading. I use the case gauge for setting the sizing die (shoulder) position. As your chamber may be different from the gauge, use feeler gauges to compare fire-formed brass to the gauge. Calipers to check cases for trim length.
 

Intheshop

Banned
You could make a case(ha) for both being comparators vs absolute measuring instruments.That is until they're calibrated against an appropriate standard......

Slight tangent for some lite reading..... look up Long Island indicators and also Mahr metrology. Once on their respective sites,look for tech articles.Keep on point,how can this article or method make your handloading "easier" WRT,all the measuring/comparing that's being carried out. It's like climbing a mountain,the further up you get,quite frequently the steeper.So if you read a book or series of papers and only get one tip....... well,you're that much closer.
 

Ian

Notorious member
Sometimes I just use a cartridge gauge and a micrometer to set the shoulder bump.
 

Kevin Stenberg

Well-Known Member
Sorry I was gone so long . Ricks link in post #6 was exactly the item i was asking about. And not being a good wordsmith i didn't know how to describe how the comparator worked. Which 5R described in clear detail.
The reason for my asking. I made a device out of UHMW (Ultra High Molecular Weight) plastic does the same thing the comparator does.
I had a piece of plastic .755 x 1.554 x 1.7 I wanted to make a to measure case length on 30 caliber cases. The hole i drilled was just larger than the dia of a fired case and just deeper than the longest neck & shouldered case i load for. So i used an 11/32" drill that i drilled .727" I show this in picture #1 & #2
Next i used the largest bit to recess the top of the jig so the shoulder would sit a little below the top of the jig. So i drilled a cone .155 below the top of the jig. Pic. #3
To mount the jig to my caliper . My table saw blade is the same width as the jaw on my caliper . So i set the saw to cut .702 deep and centered on the width of my jig. Pic. #4
 

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John

Active Member
I have an old Santa Ana Mauser they sporterized to 280 Rem. A 175 gr bullet with the Stoney point comparater Hornaday bought from them will not reach the lands and stay in the case. It still puts a 145 gr Speer in 1 1/2" at 100 yards and has accounted for more than a few animals since it came my way. Each year I consider reworking it but it still stays the way it is.
It doesn't see cast.