Brass ?


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Bullet
January 30, 2008, 11:57 PM
Are there standard specs for brass? I am interested in the differences between 9mm, 40S&W, and 10mm. What pressures can these cases really take? Do the manufactures test the cases for pressure above what SAAMI lists for the cartridges?

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ArchAngelCD
January 31, 2008, 12:57 AM
SAAMI (The Sporting Arms and Ammunition Manufacturers' Institute) sets the standards for pressures and Brass size to name a few.
Here (http://www.saami.org/) is the link for the SAAMI Home Page.
Here (http://www.leverguns.com/articles/saami_pressures.htm) is a link for a page with most of the SAAMI pressure numbers.

It's my guess like with other things in this world Brass can stand much more pressure than what the standard is, if for safety only. No manufacturer would make a case that can stand only 35,000 PSI if that's the upper limit set by SAAMI. I'm sure they build in a safety factor of at least 20% but probably much more. For example, elevator cables are tested for weight. There are 3 sets of cables in an elevator but each set of cables can operate at the maximum weight limit of the elevator. Because of the obvious needed safety requirements there is a triple redundancy built into the elevator cables. (if I remember correctly)

Steve C
January 31, 2008, 01:13 AM
The brass case is essentially a gasket in the chamber and the brass itself isn't expected to hold the pressure of the round. The chamber is what contains the pressure.

Bad Flynch
January 31, 2008, 11:52 AM
Bullet--

Indeed, there are maximum and minimum specs. for cartridge cases, as well as chambers. These cover maximum lengths, diameters at several points, rim diameter, angles, radii, cartridge case capacity, etc., etc. In order to find the engineering drawings, you will need to go to the SAAMI website and buy them, as already mentioned.

There are a couple of other sources: one of the reamer manufacturers offers a set, mostly as an adjunct to ordering reamers and the old NRA loading book had some in the back as an appendix.

QuickLoad offers some of the measurements and their companion product, QuickDesign offers more than one usually has use for. These include pressures, dimensions, capacities, tapers, radii, etc.

Hope that helps.

Hope that helps.

rcmodel
January 31, 2008, 11:53 AM
The chamber is what contains the pressure.
Exactly!

Except:
The guns design has more to due with a pistol caliber case containing pressure then the strength of the brass case.

Guns with unsupported chambers (feed-ramp cuts) are more likely to rupture a case then one with a fully supported chamber when pressure limits are exceeded.

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rcmodel

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