9mm sizing question.. Randomly checked a few and a little confused

[taymag]

So I have shot with these sizing settings for a while, and glanced up at my saami paper today and decided to check some numbers randomly.

I am not sure I'm reading this right but it looks like .3910 is supposed to be the diameter of the 9mm case around the middle.

I am measuring .372-.374 around the middle.. Can someone check in on this? Or tell me that its ok hopefully

 

[higgite]

That .3910” measurement is at .200” from the case head, not mid case. Also, SAAMI dimensions for body diameter are +0/-.007”.

FWIW, my 9mm Luger reloads measure .377” at the mouth of the case, .380” at mid case and .389” just above the extractor groove.

 

[Wreck-n-Crew]

.3910" is at the base end of the case, not the middle. The bullet end is around .380". 9mm is a tapered case design. my sizing die leaves the case before loading under .380" around .375" average and the middle graduates to .3910" at the base. Middle averages around .384" while some dies may squeeze a little more in the mid section.

What die brand and type are you using and are you using?
Either way you should be fine as long as your plunk plunk test is passing. The numbers are max diameter for 9mm chambers not minimum meet size.

 

[armoredman]

I never bothered to measure mine, to be honest - if they plunked, they were good. Lee dies, RCBS single stage press, been doing it for a few years so far.

 

[taymag]

With +0/-.007” I am pretty close. I never bothered either, just happen to be messing with 300blk converting brass the other day and printed the 9mm saami at the same time as the 300blk one and was curious.

As fast as just making sure it passed the plunk test, I was more worried about it being too narrow, I assume anything sized too small would pass regardless but may cause other issues.

Not a problem though, was just curious, I have shot thousands of rounds like this and everything seems fine

 

[Walkalong]

I have a tight chambered EMP (SAMMI minimum chamber), so I now gauge all sized 9MM brass now. If it doesn't fall out of the gauge from its own weight, I scrap it. .3915 at the base will chamber freely in my EMP, .392 is tight, and .393 will jam it up tight.

 

[taymag]

But is I were measuring below spec which is what I was making sure was ok, then it would easily fit in the gauge. Never seen the question but figured I'd ask if there were such thing as sizing too small

 

[the count]

If the rounds pass the case gauge test then you are good to go. If you don't have one you can always take a 9mm barrel and check that way.