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fbc3
04-02-2009, 08:31 PM
It's been my understanding that the cartridge case is the weakest link in retaining the pressure when a firearm is discharged. Regardless of the strength of the locked, steel action, the brass will flow and rupture if the pressure is great enough. If that's true, then what if anything makes an action superior when excessive pressure causes a cartridge case to fail? One significant difference is the way escaping gas is directed; some are designed to better protect the shooter. In terms of resisting case failure, the Remington 700 has been described as superior to a pre-64 Model 70 Winchester because the 700 provides more support to the cartridge case. If so, will a sufficiently overloaded cartridge flow and rupture in the more supportive action? Any elaboration that adds to my understanding of this subject is appreciated. Fred, Lakewood, CO

alinwa
04-02-2009, 10:56 PM
fbc3

This is really no more complicated than "the brass is the gasket, and gasket material is weaker than steel".....

Any unsupported areas of the gasket material (extractor cutouts, ejector holes, clearance between the boltface and the end of the chamber...etc) will yield.

Picture a balloon......

Surround the balloon with a sack of canvas.......

Now with the balloon acting only to SEAL the canvas against leakage you can run that badboy up to mega-pressure like 20-30 maybe even 50-60psi.

Rip the canvas though.... or leave a grommet hole in it....or otherwise leave an area of the gasket material unsupported and POP!

Same-same the brass case...

hth

al

Clark
04-02-2009, 11:26 PM
I have been trying to blow guns up, record the data, and make sense of it for 10 years.

There is a big difference between what happens in an incremental work up until the brass does not look so good.... and when that part of a work up is skipped for a much hotter load.

Brass fails in semi auto pistols when the thin case wall bulges over the feed ramp.

The brass primer cup fails when it pierces.

The brass fails when the primer pocket loosens up to the point of not gripping the primer with an interference fit.

The brass fails when the case head splits of breaks off.

There are many secondary failures that can occur as the result of gas cutting and gas blasting when the brass fails.

The brass can fail as a secondary failure when the chamber splits.

Montana Pete
04-03-2009, 12:13 PM
There are lots of ambitious handloaders out there who encourage reloading of inappropriate cartridges to high pressures.

Sometimes the weak link is a brass case never designed to be jacked up to high pressures. Does not matter how strong the action is.

Some cases like the .44 Special or the .45 Long Colt were not designed for high pressures. Conversely, cases for the .44 Magnum are rather sturdy. There will be other examples involving rifle brass, also. Such as the .45-70 even in strong modern actions.

The weak link can be the case.

Be very "wary" when reading articles talking about jacking up middle-of-the-road cartridges to high levels, regardless of how strong your action might be.

For example, jacking up .45 Colt in a Vaquero, which is a strong handgun.