9mm case gauge for MINIMUM length?

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Bobarian

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If I correctly understand what I've read here, the concern with 9mm brass is *minimum* length (.744 in) more so than maximum length (.754 in).

I see several gauges on the market that measure for maximum, but does anyone make a go/no-go gauge for measuring minimum length?

On a related note, any tips on how to properly use a caliper? I seem to have trouble holding a case exactly perpendicular to the jaws to get an accurate reading. And I've got a blister on my thumb from the wheel.

Thanks!
 
Wilson makes one that that gauges both max and min case lengths.
http://www.lewilson.com/caselengthgage.html

If you're getting a blister from the thumb wheel, you're putting way too much pressure on the wheel, which will give you inaccurate measurements, or maybe the locking screw is not fully disengaged. You can google "how to use dial calipers" and all kinds of good info.
 
Thanks, Higgite. That could be what I'm looking for. Not sure that I trust the precision of someone who doesn't know how to spell "gauge" correctly, though.:scrutiny:
 
The caliper should adjust smoothly and with little pressure. Getting the case square for a good measurement just takes a little practice. I just bought another Harbor Freight digital caliper because they mailed out flier with a $9.99 coupon for it. Even better than the $19.99 they have it on sale on the website for. While it is not as smooth as my Mitutoyo dial caliper, and not silky smooth like my Brown&Sharp, it is pretty smooth and works very well. You just cannot beat it at $10.

That said, I don't measure or trim 9MM brass and quit sorting it. It still shoots better than I can. Yes, sorting brass etc can make a difference if you are good enough, but I am not good enough off hand to take full advantage of it, and the gain isn't enough for me to go through the trouble if I could. I can still hit a 12" square steel plate at 100 yards most of the time if I concentrate (Except for bad days), while cans at 25 yards are easy, so I'm good.
 
To get the case squared up with the jaw, I cheat a little bit and use the flat ground sections of the jaws and set the case head on it. It's not the most accurate part of the device, but the difference is not important. Depending on how the caliper was made, the flat section might be zeroed with the bladed section. I have no idea.

I don't measure 9mm either. All I sort out are the pesky .380s that sneak in.
 
Measuring 9mm brass is waste of time.

Re spelling of gauge, gage is a perfectly acceptable variant. Look it up.

L.E. Wilson is the premier maker of case gauges in this country, and if they prefer gage, I think that's just fine. Merriam -Webster agrees.
 
I don't know what a "gage" is, but that is fully intentional on LE Wilson's part; I have those for many cartridges, bought across several years, and they are all marked "gage" everywhere, "gauge" does not appear anywhere on the packaging, literature, or the device itself.

For me the 9mm is used to make sure the casehead got sized enough, basically, on my match ammo. I also never pay attention to 9mm case length. Maybe it matters if you are a bullseye shooter or something... otherwise, it doesn't.
 
Moxie: You are correct, and I withdraw the aspersion. Dictionary.com was my first stop, and I did not scroll down far enough to see the acceptable variant. As a technical writer, all I can say is thanks for calling me on this.

I'm new to this hobby, so of course my inclination is to err on the side of safety and follow the rules. OTOH, the overwhelming consensus (on this forum and elsewhere) appears to be that there is little point in measuring or trimming 9mm cases. I think I can get comfortable with that.

Thanks for the feedback, everyone.
 
:scrutiny:I do case gauge my 9mm, but primarily to throw out the long ones. Why? If they stretch too long, depending on your reload gear, you may seat your bullet deeper than normal and cause an increase in pressure. This is only relevant if you’re shooting at max loads or loads close to any limits.
 
Lefty, I'm confused. My understanding is that straight walled pistol cases don't stretch.

Also, it's not clear to me how a bullet could be seated deeper than normal. If COL is measured from the case head to the tip of the bullet, isn't the distance between the case head and the base of the bullet the same regardless of the length of the case?

I can see that there would be more brass surrounding the shank of the bullet. Is that what you mean by "deeper"?
 
Seating a bullet is a mechanical function. You set your seating die based on a case (specific size) used to seat a bullet and measured and adjusted it for that. If you take a longer case and put it into the same mechanical setup the distance that the case will travel up is the same, and the distance the bullet gets set is the same. So if you have the longer case the bullet will be set at the same "physical" mechanical point which would be deepr into your brass. And i have found 9mm cases that stretch and do not fit my case gauge and tossed them. Your mechanical reloading system does not adjust for each and every piece of brass. At least not the ones i know of.
 
Case lenght variations have no effect on the internal powder space available nor the OAL, all that changes is how much the case mouth's will overlap the bullet's body. So, yeah, the press and seater does sorta automatically take care of case length differences.
 
Ranger, Yes you are correct in your explanation, but because there is more case mouth touching your bullet (i.e. seated deeper), there is more distance the bullet must travel to clear the case mouth and in turn will cause a pressure differential because it will take longer for the bullet to clear the case.
 
But it is nearly insignificant in 9MM.

A 6PPC Bench gun? Yea, now we're talking. :)
 
I would seriously doubt that your going to come across any brass that's going to be short enough to cause a problem. But if you are wanting to measure your fired brass, first re-size it. Then set it on the bottom jaw of the caliper, head stamp first. Then just keep it flush on the bottom jaw until the caliper makes light contact. It's really easy once you get the hang of feeling when it's flush and seated against the bottom jaw. And honestly, even if you make a mistake it isn't likely to be more than just a couple thous any way.

GS
 
Great idea!

A safe rule of thumb though if it is fired brass?

It must have been the right length in the first place.

I don't measure, gage, or trim auto pistol caliber brass.

If it worked the first, or the last time, it will work again.

Way too many other important things to worry about when reloading then that!!

rc
 
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