9mm luger case length


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gsc3zny
July 20, 2013, 06:07 AM
Both my lyman 49th and my lee loadbooks say the case length should be .75, but all of mine come in shorter, at .70. Nowhere that I could read did either book say a minimun length, just that the case length needs to be .75. Would .70 be ok?

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gamestalker
July 20, 2013, 07:20 AM
FYI, assuming you may be new to reloading, most specified measurements within the reloading hobby, and general firearm SAAMI component specifications are necessarily measured to the thousandth of an inch, or .001", which is three digits behind the decimal. Such is the case, and example when referring to case length, OAL, bullet diameter, head space, and other SAAMI dimensional specifications.

I don't know where you got your SAAMI case specifications from, but all of my books specify a SAAMI maximum @ .754", with trim too, or minimum if you prefer @ .744". With a case length of .700" the brass would be .044" or 44 thousandths of an inch shorter than SAAMI minimum. This would most certainly result in consistent mis-fires because the firing pin would not be able to reach the primer.

GS

beatledog7
July 20, 2013, 08:56 AM
I've never encountered 9mm Luger brass that short. Check your brass to make sure you don't have some 9mm Mak (9x18) in the batch.

Get used to being more precise with the numbers, and get a set of calipers for that purpose. If you can't measure ammo dimensions to thousandths, please stop reloading until you can.

KansasSasquatch
July 20, 2013, 09:11 AM
I'm going to take a wild guess and say that you're measuring your brass after it has been fired but before it has been resized. If that is indeed the case, resize your brass and then measure it. The other guys have made good suggestions too as far as being precise with your numbers and making sure you have equipment capable of accurately measuring to 1/1000 of an inch.

tly999
July 20, 2013, 09:31 AM
Are you using a vernier caliper to measure your brass or are you using some other device?

gsc3zny
July 20, 2013, 01:40 PM
Yes, sorry .754 is max length. All of mine come in at .701 after sizing using a Lee die and measured with a digital caliper. They are all marked 9mm luger, mostly blazer, shot unknown amount of times. I will be using Lead bullets in them. All from the same source, not sure where they got them from I measured a case before resizing die and it is .694. If loading them at this length is a reliability hazard I will take the chance. If it is a safety hazard, I guess I will dispose of them.thx

mboe794
July 20, 2013, 01:53 PM
Maybe a dumb question, but is your caliper zeroed correctly? I habitually wipe off any grime and zero mine every time I pick it up.

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