Anybody ever see this? On my 308 brass.

Those are Copper Crusher test marks.

Thats how they proof factory loads in a pressure chamber, or at least how they used to. - RCmodel can tell you more all about it !

If you have a lot of brass, I would pitch the few that have that ring. IF you do not, use them for light plinking loads, and most of the dent should fill out. It actually pushes that little circle OUT of the case wall a little, if I'm not mistaken.

http://en.wikipedia.org/wiki/Copper_units_of_pressure

GFL = Fiocchi

I have no idea about the circle marking on the brass.

Very interesting, I did not know this.

These .223 cases came out of a copper-crusher pressure test barrel at the Remington factory.

I bought 1,000 once-fired Rem cases from a scrap dealer and found these 6 mixed in.



In use, the test fixture barrels chamber is drilled for a steel piston and the chamber reamed.
Then the copper crusher slug is screwed down on top of it.

Firing the load crushes the copper slug, and it can then be measured to figure out how much pressure the load produced in C.U.P. (Copper Units of Pressure)

Here is a photo of Hodgdon's Modern-Bond pressure test gun.



rc

Interesting, never seen this before.

While I am sure the cases were used as pressure test cases I am not sure as to the method. When I see those little circular rings I tend to think more a Series 117B Charge Mode Conformal Ballistic Sensor than the typical copper crusher method.

Looking at the first link, as can be seen the Charge Mode Conformal Ballistic Sensors conform to the cartridge case, the small circular footprint they leave is pretty much identical to what I see in the posted images.

The copper crusher method as seen in the second link uses a gas check system below the base of the piston, I am not sure exactly what marks the copper crusher leaves on the case.

Really matters not as we can pretty much figure the cases were once used as pressure cases I guess.

Ron

Huh. I always wondered how they tested pressure! Ah done lernt sumpthin'!

It would bear checking them out a little closer dimension wise. I haven't heard anyone say they have found them unsafe but if they were fired with "proof" loads they may well be junk. Widners was selling some 308 cases they were listing as "test" cases...... don't know if they were actually proofing rounds or not.

TNBilly said:

It would bear checking them out a little closer dimension wise. I haven't heard anyone say they have found them unsafe but if they were fired with "proof" loads they may well be junk. Widners was selling some 308 cases they were listing as "test" cases...... don't know if they were actually proofing rounds or not.

Click to expand...

Personally while I see them as an interesting conversation piece I wouldn't load them. I have seen cases like this with a gentle ring impression to the brass punched out. For the worth of a piece of brass I just pitch them out. However, to each their own I guess.

Ron

Both copper crusher (CUP) and pressure transducers (PSI) methods use very much the same basic mechanics. Page 132 in the following SAAMI document shows it:

http://www.saami.org/specifications_and_information/publications/download/206.pdf

Other information on both systems' are covered in that sectioin. Most interesting.

My mentor that helped me when I first started reloading, has a whole bunch of these he bought from the Remington factory in Arkansas.

They are cases used in pressure testing. He uses his all the time using his full loads. YMMV though.

I have a source for brass from a ballistics lab. All the once fired brass I've bought from that source has those marks. I've loaded BUNCHES of it with nary a problem.