Dial calipers off = long 223 cases


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devils4ever
August 1, 2014, 07:33 AM
I measured all my once fired 223 cases with my trusty Mitutoyo dial calipers that I've had for decades. All cases were less than 1.750". Great. So I pressed in the primers. Then, I noticed that the dial wasn't reading 0.000 when closed. It was off by 0.015" or so. ARGH.

I just bought the Hornady dial calipers and found that some of the cases are longer than the max of 1.760" by some 4 to 5 thousandths.

I'm not sure how to safely trim these now that the primers are in. I have 2 bolt action rifles, no autoloaders.

Any ideas how to trim these safely? Or, will these chamber correctly?

Thanks.

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jwrowland77
August 1, 2014, 07:53 AM
Lock them in your bench trimmer and trim. As long as you're using a conventional trimmer, you should be fine, since nothing will be go that far down in the case.

After trimming, just chamfer and deburr with the case upside down, that way no shavings get in the flash hole. At least that's what I've done.

cfullgraf
August 1, 2014, 08:13 AM
It was off by 0.015" or so. ARGH.



You should be able to adjust the dial back to zero when the jaws are closed. There should be a lock on the dial. Nifty feature that allows you to make comparative measurements on things by zeroing the dial at any jaw position..

As long as you are not using a trim system such as the Lee system, trimming should be fine. The ls trimmer measures through the flash hole which is not possible with a primer in place.

Another watch out, if you use a L E Wilson trimmer, use caution inserting and removing the cases from the case holder. When tapping the case into the holder, you might hit the primer by mistake.

devils4ever
August 1, 2014, 08:30 AM
I have the Lyman Universal bench trimmer. There is a spring loaded ball that goes into the emtpy primer pocket in the holder. Since I have the primers in place, I'm a little nervous about putting in the case and pressing against it while trimming. Is this safe?

My calipers were off by 15 thousandths or more and was varying by a few thousandths every time I closed them. I no longer have any confidence in them.

WelshShooter
August 1, 2014, 08:37 AM
You can decap the primers out very carefully. I've done this for over 200 rounds and all went bang when used. You have to be very gentle while doing it though.

243winxb
August 1, 2014, 09:36 AM
This - You can decap the primers out very carefully. Then reinstall them after trimming.

devils4ever
August 1, 2014, 10:17 AM
I can reuse the same primers after pushing them out?

I have removed live primers in the past using the resizing die on my press, but I don't like doing it. I'm tempted to just seeing if they'll chamber in my rifles. The longest is about 1.765".

jmorris
August 1, 2014, 10:21 AM
One reason I like a case gauge, like a standard, it never loses zero.

spitballer
August 1, 2014, 10:46 AM
I still use my original Lee trimmer with an electric drill. It trims to about 1.75". Afterward I spin the chamfer tool a couple of times before taking it loose from the shellholder. Simple and easy.

Sorry, just got the gist of your message - primers already installed. If it were me, I'd sacrifice the primers.

rg1
August 1, 2014, 11:52 AM
Also, if 'zero" isn't in the correct place at the top of the dial you can take the caliper apart, rotate the gear teeth and get it back to position. Possibly the gears have slipped a tooth? Takes a tiny screwdriver.

Tilos
August 1, 2014, 11:54 AM
Know that a dial caliper can jump a tooth, that usually is .020", depending on the dial layout (0.100 or 0.200/rev) a small tool comes with many calipers to set it.
It's a small/thin (0.015") thing that most never know what it's for.
If you don't have the tool a straightened paper clip can be used.
:D
show that caliper some love, clean and lube the rack
if you have the old padded type case, look under the padding for this tool;)

243winxb
August 1, 2014, 12:24 PM
I'm tempted to just seeing if they'll chamber in my rifles. The longest is about 1.765". The odds are in your favor that there will not be a problem. Are you feeling lucky? :uhoh:

jcwit
August 1, 2014, 12:36 PM
One more time, primers are set off by impact, not by slow pressure. Sudden pressure ie: impact by a firing pin sets off the primer.

You will be fine using your trimmer.

carbine85
August 1, 2014, 01:10 PM
Maybe I missed something here. Why all the talk about removing primers? Just trim the cases and move on. I don't see a problem.
You said they are bolt guns. I'm betting they chamber and shoot just fine as they are.

243winxb
August 1, 2014, 02:15 PM
Carbine85, the Lyman Universal trimmer needs the primer pocket empty.

GLOOB
August 1, 2014, 07:37 PM
If your rifle is amenable to a chamber test, I would go that route.

I would measure each one with a good caliper to find the longest half dozen cases. Then I'd test those cases. If they pass, then I'd load those cases with no crimp and try again. If those pass, I'd load and shoot the rest without worry.

If this works, you get a bonus. You can now put off trimming even longer, lol. Write that length down and subtract a little for your new must-trim length.

For all you know, your rifle might be able to handle cases that are 1.785!

I wonder, if your chamber is cut right, and you let your brass grow, can your chamber start acting like an X die to limit the maximum length? Oh, of course not, duh... when sizing, the brass lengthens.

devils4ever
August 2, 2014, 07:28 PM
Okay, I took a chance and trimmed the primed cases without incident. It wasn't easy in the Lyman trimmer since the spring loaded ball wasn't able to fit into the primer pocket. But, I took my time and did it very carefully. Everything went fine. I did about 30 cases this way. Some cases were over 1.770"!

I took a look at my Mity calipers and they did have a small flat tool to reset the zero. I did it, but the zero kept shifting every time I closed them. Something is not right. The Hornady calipers I just bought are right on. They look like excellent quality. I hope they stay that way. Anyone want to buy a non-working Mity calipers? :D

gamestalker
August 3, 2014, 08:51 AM
Your concern of whether or not they'll chamber isn't really relative as to why we must maintain SAAMI trim lengths.

When a bottle neck case exceeds the SAAMI max head to mouth length, it will very often chamber without any noticeable difference. The reason for trimming brass is because the mouth can get pinched / restricted in the throat during firing. This prevents the mouth from expanding adequately, which creates a pinching effect of the projectile and prevents it from freely leaving the case mouth, that's when pressures can go unpredictably and dangerously high, and why we trim our brass.

Chamber fit, which is what you are referring to is controlled by the resizing die by how far the shoulder is bumped and sized case body diameter. Also, if a bullet is seated to long, in other words, when completed cartridge over all length is to long, the projectile will engage the lands, thus preventing proper chamber fit of a cartridge, this as well can drive pressures up.

GS

Zeke/PA
August 5, 2014, 06:39 AM
Also, if 'zero" isn't in the correct place at the top of the dial you can take the caliper apart, rotate the gear teeth and get it back to position. Possibly the gears have slipped a tooth? Takes a tiny screwdriver.
This .015 error probably occurred when apiece of "dirt" in the gears made the dial "skip".
A thin piece of brass inserted properly between the gears will "skip'" the gears to your advantage. Mitutoyo once furnished a similar brass tool with their calipers.
It's a good habit to check the zero on dial calipers before each use.

eam3clm@att.net
August 5, 2014, 11:05 AM
It sounds like a good reason to get a WFT to trim your brass. It indexes off the case shoulder

jcwit
August 5, 2014, 11:31 AM
Or a Lee Trimmer set up, I know I like mine better than my Lyman trimmer.

As far as the calipers, get a digital one, they are only 10 bucks at Harbor Freight, ya I know, you need batteries for them, want cheap batteries, buy a couple of those LED pointers/kitty toys, the cheap ones, they use the same batteries. Throw the pointer away and use the cheap batteries, cheaper than buying batteries from Menards or Walgreens or even WalMart.

bmnloader
August 5, 2014, 12:12 PM
Look for a small chip or piece of trash in the gear rack of the calipers. We run into that a lot here in the shop. It doesn't take much. Usually just blow them out and reset the zero with a small paperclip as described above.

jcwit
August 5, 2014, 12:20 PM
Careful how and where you blow, I've blown the lens off calibers already.

bmnloader
August 5, 2014, 01:07 PM
Yes you can! A can of air will work or you may need to get a magnifier and look up close to the end of the rack, it won't be very big if it's there. I've got Mitutoyo calipers 20 yrs old that still work fine. They not Starret but close.

1911 guy
August 6, 2014, 01:40 AM
I use calipers many times a day at work and have made the habit of checking zero every time i pick them up, even if i have just set them down a minute ago. Same with mics. The standards are right there next to the mics in my box, why not use them?

devils4ever
August 6, 2014, 11:18 AM
Point well taken. I will zero the calipers from now on before use. Also, I will use my 1x2x3 block on occasion to verify readings.

Zeke/PA
August 6, 2014, 11:39 AM
I use calipers many times a day at work and have made the habit of checking zero every time i pick them up, even if i have just set them down a minute ago. Same with mics. The standards are right there next to the mics in my box, why not use them?
0 to ones? Careful anvil to anvil closing. Two inch mics and up? Use the "standards" held with a wooden cloths pin. For REALLY precise work , the mics should be checked OFTEN, preferably by the same shop "Guru"!

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