Cheap case comparator

5

5whiskey

New member
Someone here has mentioned options for an inexpensive case comparator before. I realize hornaday makes one that isn’t crazy expensive, but $40 is $40. If I can make a homemade option work for $10 that is pretty accurate I would rather do that. I would rather sink the extra money in a better quality caliper than what I have. Plus I’ve decided I want an actual nice micrometer and not an el cheapo as well. Going to stop being “that’ll work well enough” in sizing and case prep and actually try to be more exacting. My personal belief is a better way to achieve this is in better quality measuring instruments than to spend 50 bucks on a piece of steel that doesn’t have to be a standard length, and measures comparatively. FWIW, I’m not a machinist, but I’m ok with a drill press, file, etc. I’ve made dovetail pistol sights by hand before that worked like a charm. I‘m not a pro, but I can fabricate and I like the challenge.

*snicker* says the man that defends the frankford arsenal digital scale.
 
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Yeah you can use up side down cases with primer removed . Like a 40 S&W for 308 would work . Unclnick aways post a pick of the common washer/spacer that works great but I forget the exact name .

With a little imagination there’s all kinds of things you could use . The key to a homemade comparator is to be sure you always use the exact same one never switching them out for a new one . Any variations from one insert to the next can change your measurements
 
go to your local hardware store and look for bushings, offsets etc . Might see if you can find just the Hornady anvil and the size bushings that you would be using most often also to save money. I only use about four of those inserts, the .330, .350, .375 and .400 which covers .22 through .308.
 
go to your local hardware store and look for bushings,
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Word of the day lol :D

A drill jig bushing or stem bushing with the correct inside diameter for your cartridge case or bullet . The bushing I was thinking of is the type of bushing you find inside a skateboard wheel in between the bearings :) ( correct diameter for your purpose of course ) ;)
 
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I have two questions, first, what do you expect a comparator type tool, (homemade or otherwise) to do for you??

Second, do you have firearms that would actually benefit from you applying what ever it is that the comparator tells you??
 
Here's an old photo I've posted before using a steel spacer.

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Honestly, I really prefer the Wilson headspace gauges. You get min/max case and neck length. You can also use the gauge like hte spacer/comparitor to measure head space. Yes they are about the same price as the comparitor kit, but much more useful IMHO.

On a side not. Check the specifications for accuracy for the micrometer. I have recently learned that most calipers are only accurate to +/- 0.001... expensive calipers and cheap ones alike. Make sure it has the accuracy you need, to do the work you are trying to do. If the accuracy is the same, you gain nothing by buying the more expensive ones.
 
I have two questions, first, what do you expect a comparator type tool, (homemade or otherwise) to do for you??

Second, do you have firearms that would actually benefit from you applying what ever it is that the comparator tells you??
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Ha see I am glad you asked those questions. I actually have logical answers.

What will a comparator do for me? Well, it will allow me to actually measure and FL size my brass as little as possible to still chamber and fire. There are actually other ways to do this I know. One is to screw out the size die until it’s obviously oversize, and then size and adjust in increments until it just chambers easily/normally. This works quite well on modern cut chambers and is the method I have traditionally used. But a case comparator is much quicker and easier to adjust dies to size brass as little as possible (and necessary). And there are some rifles with which the slow method I just described are not friendly too. The straight pull Swiss rifles are hard to gauge differences in closing pressure. Cock on close rifles also are a little more difficult to get the slower method I described right.

As to the second question, do I have a firearm than can benefit from this? Yes. I shoot milsurp rifles a lot, ones known for having notoriously... oversize chamber dimensions. Sizing brass as little as possible can possibly squeeze out an extra firing or two with brass that is already hard to come by, or brass that I take time to reform.

Unclenick thanks that’s what I was looking for. This should work for most of my chambering.
 
Is this what you are looking for?
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Not at all.

As for the price there is an old saying that applies "Buy once, Cry once"
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The logic I am finally going to use with my measuring instruments. Other than the $3 steel bushing that would likely work just as well for my needs, 90% of the time, as the hornaday case comparator that costs more than 10x that much.
 
Ok, I think I get what you are doing...but you still have to adjust your sizer die.

But a case comparator is much quicker and easier to adjust dies to size brass as little as possible (and necessary).
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I don't really see how...

Seems to me the least amount of sizing possible is a case fired in your rifle, with only enough of the neck sized to properly hold a new bullet. And to do that, you need to set your sizer to do that, so what does the comparator do?

I understand what you're saying about not sizing more than what is barely needed, I neck size for a WWI .303 British. New or "once fired" brass gets a FL sizing, then after that, neck sizing only. And I have given up on "once fired" brass (in .303 Brit) pretty much, decided that any addition or replenishment of my case stock will be new brass. There's no way to tell if brass sold as "once fired" is ONLY once fired, and after I had a complete head separation of a case on MY first firing, I decided the cost of new brass was justified.
 
I can’t remember who makes it but there is one that’s shaped like a big nut and each of the facets has a hole in it for different sizes. So you get the six most common used sizes in one easy to use tool.

Oops, I did a little research after my post and realized this tool is for measuring bullet seating depth at a datum point on the ogive.
 
but you still have to adjust your sizer die
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Yes I know this. So it goes like this. I currently have a safe setting on all my dies and they are locked in to a turret ring or quick change bushing. Safe, but probably not optimal. This was done by careful trial and error. So, I take fired case, measure it with the comparator. I then adjust dies out (a significant amount, enough that they should be sized too long), I size a case, and measure that with the comparator. When my sized cases read about .001 under the fired and unsized case, then I should be sizing about a good minimum but reliable amount.

I have done this without a comparator. With a cock on open traditional bolt action. I can feel crush fit when sized too long. I adjusted the dies so that I’m literally a “smidge” of a turn past that crush fit feel (yes a smidge is a technical term lol). It is difficult to do this with a cock on closing, because the “feel” isn’t as sensitive. It’s almost darn near impossible to do this with a straight pull bolt ala K31. So a case comparator will help me get what I’m looking for. And there’s not point in dropping 40-50 bucks on one when I know there’s a 5 dollar item out there that will literally work just as good.

I also don’t need interchangeable bushings for different neck diameters. 90% of my shooting is .308-.312 projectiles. I do have some slightly different shoulder profiles, but not by much.
 
It is difficult to do this with a cock on closing, because the “feel” isn’t as sensitive.
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The way you get around that is to simply remove the firing pin and spring assy from the bolt. If you're using something with a spring loaded ejector in the bolt face, remove it, too. Essentially strip the bolt down to what you would do using a headspace gauge and then use factory ammo to learn the feel of it, so you can compare that to the feel your reloads give you.

I'd imagine the same thing would work with a K31, remove everything that adds load or resistance to the bolt so all that's left is what the case generates when you chamber it.

I've been loading since the early 70s, have been set up to load for over 30 different rifle and handgun cartridges, and my ammo fits my guns and works fine, shooting at least as well as I do and often better, all without a comparator or min/max case gauges. I use a caliper and (rarely) a micrometer and my guns to test and measure for fit. And I nearly always full length resize, my brass lasts a good half dozen cycles or more sometimes a lot more. I don't load for match shooting, or getting the smallest groups, most of my guns aren't made for that anyway.

I do have a couple varmint rifles that will go sub MOA and I don't use the tips and tricks the benchrest shooters do to get them there. Maybe I'm just lucky?? :rolleyes:
 
^44 I don’t disagree with your points. I understand I can set dies up without a comparator. I’ve not been doing it since the 70s, but I have been doing it 10 years. I’ve never used one before. I want to try, and the goal is to extend brass life some.

You make a good point with the COC, were it just that action type I probably wouldn’t be stressing over trying a comparator. But the straight pull poses a different challenge. I’m not sure I can manipulate the action with the spring/firing pin removed it’s been a while since I disassembled the bolt. And the semi-auto Garand (though my case clearance will be closer to .003 in the Garand) cannot be sized as close as possible with the old traditional trial and error chamber fit. Or maybe it possibly could if I sit down and think about it, but I also bet a comparator would make the process go quicker.

I also have a rifle/ammo combos that shoot sub moa. My .270 load out of my savage 110 is good for 2/3rd - 3/4 moa all day every day. My better loads for AR I put 10 rounds within a 1.5” group once at 100 yards. Every 5 round group I’ve ever shot using that load in my primary AR is under moa groups. The comparator isnt to eek out moa... a rather futile endeavor with shooting iron sights with my eyes out of 80-100 y/o battle rifles.
 
As long as you can strip a bolt to its body, you can generally feel the fit. With the Garand, the stripped bolt body's extractor shank hole will accommodate a drift punch or a nail down to use as a bolt handle to move the bolt forward and rotate the lugs. I've used that arrangement for a little very light (don't want to remove the carburizing) lug lapping in the past.
 
And the semi-auto Garand (though my case clearance will be closer to .003 in the Garand) cannot be sized as close as possible with the old traditional trial and error chamber fit. Or maybe it possibly could if I sit down and think about it, but I also bet a comparator would make the process go quicker.
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Considering all the decades that passed before comparators became a thing, I'd say certainly you can do it without one. Using one might make the process go quicker, seems like it ought to, but its not a process I use, or am interested in.

For one thing, I DON'T want my brass for semi auto rifles sized as tightly to the chamber as possible or practical. I WANT a bit of a "loose fit" (relatively speaking) so the rounds reliably chamber, and I get that using my FL sizer die with a firm contact with the shellholder. I don't do "cam over" and I'm willing to give up a (possible) couple cycles of brass life in exchange for dependable feeding.

I'm not feeding a Garand with reloads (Garand went to someone who really, really wanted it) but I do feed my M1A my reloads replicating GI ball, and it runs well on them.

Brass is, ultimately, and expendable item. Kind of like the tires on your car, if you use them, at some point, they get worn out and unsafe for further use.

I can see the point to minimal sizing when feeding a manual repeater, to extend brass life by reducing the amount the brass gets worked. But in a manual repeater, you are the "action spring" so you can easily compensate in a way the semi auto action cannot.

If what you're doing works AND you get some actual, noticeable benefit to doing it, go for it. Otherwise, why bother??
 
Unclenick thanks for the spacer that was what I had seen before. Funny thing I couldn’t find one at Lowe’s yesterday but I did find a 3/8 bronze flange bushing that works perfect. I chucked a case in the drill press and lapped it a little with valve compound so I can have a little more contact than one thin line on the shoulder. The concept works great. Just as I suspected, I was sizing 7.7 jap a bit more than needed.

I know brass is an expendable item. At the same time, brass for 7.5 Swiss, .308 British, 6.5 carcano, or 8mm lebel isn’t easy to find when there isn’t a component shortage, and it’s still not cheap. These days? I’ll do what I can to make it last (safely)
 
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