Found this 9mm Luger ammo vs 9mm

[DonVoigt]

Ok,
great references.
But the 9mm does headspace on the case mouth, no matter what sammi "x'ed".
Just as soon as one has a minimum case in a maximum chamber, the "x" moves immediately to the case mouth.
The "x" only enters the equation in the imaginary world of engineeers. JMHO

[Kyrie]

Originally Posted by DonVoigt

Ok,
great references.
But the 9mm does headspace on the case mouth, no matter what sammi "x'ed".
Just as soon as one has a minimum case in a maximum chamber, the "x" moves immediately to the case mouth.
The "x" only enters the equation in the imaginary world of engineeers. JMHO

Don is generally correct, if a little off conceptually.

"Headspace" is a characteristic of a firearm's chamber, and not a characteristic of firearm's cartridge.

In a 9 mm Luger barrel that is properly dimensioned with a correctly cut chamber the headspace datum line will be located in the chamber between .754 and .776 inches from the standing breech when the firearm is in battery.

A correctly dimensioned 9 mm Luger cartridge will have a case with an LOA (case head to case mouth) between .754 and .776 inches in length.

The verbal shorthand for those two paragraphs is "A 9 mm Luger cartridge takes its headspace off the case mouth."

[Rick W.]

Over the years, I have often wondered about the SAAMI organization and its functions in the states. Is it a mandate or a suggested set of data?

I knew it was a dimensional reference to try to commonalize ammo and chambers here. Guess some definition for the industry needs to be in order to have interchangeable ammo and firearms(chambers) and to veer off such is a financial/physical risk. The wrath of a shooter that cannot chamber a cartridge in his weapon is a force to be reckoned with huh?; much less one that got hurt and the litigation that follows for years.

The circled X to me has always been just a dimensional identifier, nothing else. The numbers tell the story. Not a M.E. here.

The 754-776 is the go and no go chamber dimensions, take a reading on your gages. Interesting to note that a case can be 744, and in a max chamber of 776, looks like some stress is put directly on the extractor. A lot of once fired brass is shorter than the 754 number, probably for edge in commonality.

Some gunsmiths will chamber a minimum chamber, trying to help out the fit of case with today's brass. Some will give more slack, and comes down to philosophies. Combat weapons need to go no matter what, competition guns that need the accuracy; get the tighter fitment.

I now remember Mark1 talking about other standards for the min/max of the 9mm. The numbers he mentioned pretty much are like what most smiths will chamber a new 9mm barrel to in final breeching. Tighter numbers.

When I first got into reloading, we all rolled crimped. Revolvers got a heavy crimp, autos got a light crimp; since we all knew how things headspaced right? Then the advent of the taper crimp available dies, and now even the collet crimp. So some advancements have been found over the years.

Of course, our friends across the big pond have their own version of a controlling or voluntary mechanism. With all the pictures I have looked at of vintage chambers in 9mm(thanks to all here) I have not learned enough yet about their dimensional data; maybe some day, but for now..........I have to live with today's brass dimensional data.

[Kyrie]

Originally Posted by Rick W.

Over the years, I have often wondered about the SAAMI organization and its functions in the states. Is it a mandate or a suggested set of data?

The Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) is a private organization created in 1926, recognized by the American National Standards Institute (ANSI), and privately funded by companies, organizations, and individuals with an interest in the manufacture of sporting arns and ammunition.

SAAMI serves as the clearing house and reference center for the data need to insure uniformity of firearm critical dimensions and the uniform compatibility of the ammunition manufactured to be used in those firearms.

Firearm/ammunition manufacturers’ adherence to SAAMI manufacturing data is voluntary.

Originally Posted by Rick W.

--- snip ---
The 754-776 is the go and no go chamber dimensions, take a reading on your gages.

Actually, no. These are the inch pattern lengths of the GO and FIELD REJECT headspace gauges. There is no SAAMI standard for a “NOGO” gauge.

Originally Posted by Rick W.

--- snip ---
Of course, our friends across the big pond have their own version of a controlling or voluntary mechanism.

For most of western Europe countries (the EU in particular), this is Commission Internationale Permante Pour L'Epreuve des Armes a feu Portatives (C.I.P ). That’s also true for the arms/ammunition manufacturers in other countries who wish to market to those countries who are signatories to C.I.P.

For C.I.P. signatories, C.I.P. standards are supposed to be legally obligatory. The degrees to those obligations have been observed has varied from country to country, and from proof house to proof house, and from time period to time period.

At the risk of blending threads, C.I.P. and NATO have a lot in common when it comes to making and complying with agreements.

[Rick W.]

I always had the concept that the SAAMI deal was voluntary. Voluntary from a business sense I guess.

Most of the reamer vendors offer go, no go, and field gages. I have never seen a field gage in the hand, only in pictures. I measured a set of 9mm gages a while back, curiosity you know, and they measured 754 and 776. Were marked go and no go..............go figure huh?

I was surprised that the European standard was tighter between the go and no go(some slack please). In today's environment, tis probably the more better spec to me at least.

Maybe some poetic license or semantics by us in the colonies huh?...