Hornady Head Space Comparater

nettlle

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Trying to figure out if I need one or not. Never used one. If my cases pass a case gauge and chamber easily why would one be needed?
 
It's advertised to extend case life. What dimensions would one be trying to achieve and how would you adjust the die for it? Does a small base die cancel the adjustment option out?
 
By backing it out a little bit at a time to achieve just barely enough sizing to chamber freely in the rifle. For instance in a bolt gun, moving the shoulder .002-.003 less than a case fired from that gun is a pretty common thing. In semi-autos it usually should be more like .004-.005 for reliability. Can still be done with SB dies, as it's the shoulder you're sizing to not the base.

When sizing for rounds that may be used in multiple rifles I try and shoot for .004 less than the shortest chamber.
 
It's advertised to extend case life. What dimensions would one be trying to achieve and how would you adjust the die for it? Does a small base die cancel the adjustment option out?
It’s to keep from having case head separations, and that’s it IMHO.

A couple of thousandths for bolt guns (1/2), and 3 thousandths for most semis (3/4). No one hits it dead on with every case.

You can do this a number of ways, all acceptable if done correctly.

The good news is that rifle makers and die makers do such a good job, most people don’t measure anything, just size the max their die goes, loads, shoots, has fun, and stays out of trouble.

Some of us like to have more control/sleep better at night.
 
I want all of reloads exactly the same as the ones before. All of my notes indicate how much I set back the case particularly if I'm full length resizing. In my experience set back does make a difference. It's a handy tool, and I use mine all the time.
 
In my opinion if you are going to load many bottleneck rifle cartridges it is a "nice to have" item. Your ammo will likely funtion fine if you just FL size with your die run all the way down to the shell holder as the instructions say. It might not be best for case life but it will function just the same. If you want to fine tune your shoulder set back and extend case life you might want this tool.
I have one, and use it sometimes since I have it.

-Jeff
 
@AJC1 may back me up on my thinking…
Some chambers will STReeeeeeeeTCH cases something fierce, much past what a sizing die touching the shellholder will size them at (see 7.7 Arisaka chambers and alot of 30-30 chambers). 🤪
A comparator is a good resource tool to have for those situations……IMO
 
I find modern guns have very close chambers and if your just banging away with a nato caliber 223/308 in a semi auto you probably don't care at all. If your in the search for accuracy, better case life, or saftey with old milsurps you probably need one.
 
I load a lot of .223, with a couple different recipes. But I assume that every round could be needed for defensive purposes. Therefore, I have a maximum length for base to datum that will work in all my rifles, hoping that this will provide the best chance that every round will chamber properly. I use the Hornady comparator on every case during sizing to make sure that none of them exceeds that maximum length. It's worked for the past 17 years. Note that I am not making these to be precision rounds and I do use a small base sizer as well.
 
I am banging away with a 308 M1A and have read that brass life is only 3-4 reloads. Considering the gauge to possibly prolong brass life. Good 308 brass isn't cheap. When I bought the M1A I also bought a few hundred factory loads to hold me until I got 308 set up on the loading bench and to give me brass to start out with. I already have (4) reloads on some of this brass and I see no sign of case head separation. Maybe reload these a few more times to see if these rifles really are the case eaters folks say they are.
 
a headspace comparator is not "needed" in any way for reloading ammunition for any type of firearm.
If the Gentle Reader is going to simply full-length resize every case, of every manufacturer, of every work-hardened condition,
of every spring-back tendency, for every gun -- and discard said cases after 'x' cycles ('x' being a number as small as 5-6), so be it.

If longer life is desired -- with some engineering "feel" as to most efficient headspace -- for any given gun/case manufacturer,
condition (et al) -- I do recommend disciplined use of the comparator checking setting up of the die.
 
If the Gentle Reader is going to simply full-length resize every case, of every manufacturer, of every work-hardened condition,
of every spring-back tendency, for every gun -- and discard said cases after 'x' cycles ('x' being a number as small as 5-6), so be it.

If longer life is desired -- with some engineering "feel" as to most efficient headspace -- for any given gun/case manufacturer,
condition (et al) -- I do recommend disciplined use of the comparator checking setting up of the die.
Well spoken. Something well worth considering.
 
I am banging away with a 308 M1A and have read that brass life is only 3-4 reloads. Considering the gauge to possibly prolong brass life. Good 308 brass isn't cheap. When I bought the M1A I also bought a few hundred factory loads to hold me until I got 308 set up on the loading bench and to give me brass to start out with. I already have (4) reloads on some of this brass and I see no sign of case head separation. Maybe reload these a few more times to see if these rifles really are the case eaters folks say they are.
We may have a diverging concept here.... that gun is very hard or brass and minimizing brass movements will help, but it's not a one stop shop for lifetime
 
Only trying to minimize the damage to the brass. Have not done well at minimizing movements by my use of a small base die.
 
Only trying to minimize the damage to the brass. Have not done well at minimizing movements by my use of a small base die.
My 7.7 has a long chamber with a fat base. I'm picking up what your putting down, smoked expensive cases on the first firing.... you can try some advanced techniques like creating false shoulders on brand new cases, to blow the shoulder forward minimizing that first cycle death throw.
 
Would one be advantageous when loading for a rear locking bolt action? I have read cases do stretch more. The action in question is Carl Gustav 3000 (Sauer 80)
 
If the Gentle Reader is going to simply full-length resize every case, of every manufacturer, of every work-hardened condition,
of every spring-back tendency, for every gun -- and discard said cases after 'x' cycles ('x' being a number as small as 5-6), so be it.

If longer life is desired -- with some engineering "feel" as to most efficient headspace -- for any given gun/case manufacturer,
condition (et al) -- I do recommend disciplined use of the comparator checking setting up of the die.

This doesn’t make any sense - you’ve presented some false paradigm for comparison of use cases which has no bearing in actual practice. There’s certainly no support for your implication that using a comparator will improve case life, and speaking as an engineer myself, I can’t fathom what could be meant by “engineering feel.”…

A comparator is not the only way, or even the best way, to set case dimensions specifically for individual rifles. It’s only a reference tool - we can do the same process as the comparator by simply using our actual rifle chamber to feel for headspace kiss, then use the depth spindle on the caliper to sink the seating die our desired shoulder bump. Doing this with the actual rifle chamber itself avoids some of the common traps some reloaders fall into due to action type design - for example, the observed case stretch during cycling such fired cases are even larger than expected, so bumping 2 thou from fired - rather than 2 thou from kiss length - may still be oversized for the chamber, or the opposite when a rifle with a sloppy chamber may still allow once fired brass to close freely, so bumping this brass back 2 thou from fired length will produce undersized brass, even smaller than the 2 thou undersize target… so blindly following process with a comparator ignores certain realities, which aren’t good for the Gentle Reader to ignore…
 
Would one be advantageous when loading for a rear locking bolt action? I have read cases do stretch more. The action in question is Carl Gustav 3000 (Sauer 80)

Read my response above. Rear locking actions with excessive case stretch are another example where blind use of a comparator instead of using the actual rifle can lead to improper set up of the die, and then feeding and extraction can be compromised.
 
A comparator is not the only way, or even the best way, to set case dimensions specifically for individual rifles. It’s only a reference tool
That's why it's called a comparator. Moreover, using the (average) fired case as reference point* for the comparator is exactly what I would recommend for individual rifle chambers, and is one of the easiest ways to set dies for a specified case manufacturer, work-hardness or springback conditions with any particular lot of cases -- or individual cases in mixed-lot/manufacturer sizing sessions.

In the latter instances -- all cases in a sizing session nor reacting the same -- oft times a second "bump" is required to settle the shoulder. In that instance quick & easier use of the comparator is a godsend.

* postscript, the Gentle Reader can also use "closing kiss" to establish reference point, but it's the comparator that provides what that reference point is digitally.
false paradigm for comparison of use cases which has no bearing in actual practice.
post-postscript: In fact I do use the above in actual practice. :cool: :thumbup:
 
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I own the Hornady tool - and multiple versions from multiple companies - but I rarely make use of them, and will say, with absolute certainty, a headspace comparator is not "needed" in any way for reloading ammunition for any type of firearm.
I will disagree with you on this one.
I load 5.7x28 and the amount that the shoulder moves on each firing is insane.
On my first attempt to reload 5.7x28 I tried to push the shoulder back to where it was supposed to be and my die wouldn't do it.
I had to remove 0.002" off the bottom of the die to get it there.
My comparator set didn't have a small enough bushing to accomodate the 5.7x28 cartridge so I used a 26 cal bushing.
Without a comparator there was no simple way to calcualte how far to push the shoulder back.
I also use one for setting up my sizer for my M1A National Match to work the brass the least amount possible

5.7-1.jpg
5.7-2.jpg
 
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