Did I ruin my brass?

[grubbylabs]

I washed it after tumbling and sizing to get the extra lube of it and I set it in the oven at about 350-375 and then started doing some dishes and forgot about my brass

 

[.284]

How long was it in the oven?

 

[mehavey]

... and how many did you actually bake?

 

[Slamfire]

Brass Annealing:

Handloader’s Manual

Early Naramore, Major Ordnance Dept Reserve, Small Arms Publishing , 1937

“The best and surest way of drying cases is with the use of artificial heat, but care must be taken not to overheat them, as too much heat will soften the brass and may render it incapable of withstanding normal pressures. Most modern stoves, whether electric, gas, or coal, have oven thermometers that are, at least, fairly accurate. For stoves sold in the United States, these thermometers register degrees Fahrenheit and brass can be heated up to 428 degrees Fahrenheit without undergoing any change in its grain structure. For drying cases it is best to keep the temperature as low as 300 degrees. This heat is amply high for the purpose and offers a liberal allowance for any inaccuracy of the thermometer. If you oven has no thermometer, one can be purchased at small expense in almost any department or five and ten cent store. The thermometer should be placed near the cases as the temperature will not be the same in all parts of the oven. It is also well to place the cases on one of the sliding shelves or racks, away from the bottom of the oven, or the heating element if it is an electric stove.”

I doubt anyone has coal fired ovens anymore; this was written in 1937.

After reading Major Naramore’s book, it is obvious that the gentleman had a technical education in materials or materials engineering. He also worked in an era when the Army actually made rifles, cannons, cartridges and had research labs. Today everything is contracted out and data sharing just does not exist between contractors or anyone else. But then, he could call up an Army buddy and find out who and whom had material data on cartridge cases.

I am surprised that brass will anneal at 428 F, I would have thought, based on the diagram I have, that it is much higher. Still, I put my oven on low, and in a half hour or so, my “five and dime” store thermometers read 212F, and don’t go any higher. Since water boils at 212F (at sea level) I know my brass is dry. I don’t set the oven any higher than warm because all the grease in the oven evaporates on my brass, if the oven temperature increases by much.

 

[grubbylabs]

Just under 50 pieces and at least 30 minutes.

I did not think about it when I turned the oven, I just turned the dial and then started unloading the dishwasher so I could re load it.

 

[Dave R]

Looks like at 375 you have just begun to affect tensile strength. The graph is barely curving downward.

OTOH I'm not sure the risk of a catastrophic case failure is worth 50 pieces of brass.

Slamfire, that is an awesome resource! Thanks for reminding me why I love TFL.

 

[Unclenick]

Grubbylabs,

Your brass is likely just fine. I assume your oven temperature was in °F? That chart is in °C. 375°F is only about 190.6°C. Nowhere near the stress relief temperature (starts at about 250°C or 482°F), much less being near the softening point on the chart. If your oven is in °F, you got nowhere near to altering the brass properties.

 

[SL1]

The problem is

that you don't know what temperature your brass actually experienced in your oven, because you didn't put a thermometer near the brass. If the brass, especially the case heads, were near the heating element at the bottom of the oven, then they could have seen substantially higher temperature than the thermostat in the oven that was controlling the heating elements.

I'm with Unclenick in thinking that you PROBABLY didn't ruin your cases. BUT, I think caution is in order. You didn't specify what cartridge you are loading, but the picture looks like .308 Winchester. If so, the it is a pretty high-pressure cartridge that can hurt you and/or your gun if the case head fails. SO, it might be a good idea to load a few to mild pressure and mike the case heads before and after firing to see if the expand. If they do, then you DID ruin your brass. If not, then work-up to normal loads in a few steps, checking for case head expansion at each level.

SL1

 

[mehavey]

Brass is real cheap compared to all the [potential] price-to-get-well/fix-it consequences. (And what price peace of mind?)

Fork over 25 bucks for another bag of brass and chalk it up to a relatively inexpensive learning experience.

 

[CrustyFN]

I noticed the chart is in degrees Celsius. At 375 degrees Fahrenheit you should be no where near where it shows the brass being affected. At 375 degrees F you are at 190.5 on the degrees C chart.

 

[mapsjanhere]

From a materials science point of view it's most likely fine. From a "would I put my face within 4 inches of it while I rely on it to hold back 50,000 psi" point of view - hell no.

 

[Edward429451]

I never go above 250 F to drive water off and crack the oven door for the humidity to escape.

 

[DANNY-L]

If you load them start with just a few at starting load from your manual and check them after firing and go from there. Increasing slowly if you continue.

 

[grubbylabs]

Since I am not an engineer I think I will let the brass go. I just don't see it being worth 25 bucks.

And yes it is 308

Most of it was scrounged up at the range any how.

 

[swmike]

When I want to dry brass I just put in a pan in the oven and turn on the oven light with the door closed. When I wake up in the morning it's all dry and never got too hot to touch.