Can drying brass at 140f cause the brass to change shape? I wet clean my brass, dry it in an old air fryer for 30 minutes at 140, then resize, clean/dry again to remove case lube. If I trim after the second clean/dry, I notice that the case mouth is undersized. My Lee trimmer won't fit in and I have to run the expander ball through it again. Could this be from the heat of the dryer? Is 140f hot enough to damage the brass?
- Thread starter Squad51
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No, thats not enough heat what you are seeing is "spring back" in the brass I believe
Yeah, you should wash using the cold cycle to avoid shrinkage.
Now I’m confused. I thought that was how you caused shrinkage. 
By any chance are you measuring the case mouth after sizing? I’d say that’s where your case mouth size issue will show up.
If that’s not it then check to make sure that the case mouth isn’t peening in a bit during your second clean/tumble. Do you ID and OD chamfer them?
By any chance are you measuring the case mouth after sizing? I’d say that’s where your case mouth size issue will show up.
If that’s not it then check to make sure that the case mouth isn’t peening in a bit during your second clean/tumble. Do you ID and OD chamfer them?
I do ID/OD chamfer after trimming. I will measure case mouth after sizing and again after cleaning on my next batch.Now I’m confused. I thought that was how you caused shrinkage.
By any chance are you measuring the case mouth after sizing? I’d say that’s where your case mouth size issue will show up.
If that’s not it then check to make sure that the case mouth isn’t peening in a bit during your second clean/tumble. Do you ID and OD chamfer them?
No, the brass will not change shape or shrink from that heat. What you seem to be describing is what normally happens after sizing . . . it's called "spring back". Depending on how work hardened the brass is the more spring back will occur and the sooner it will occur. Allowances for this spring back needs to be made for those who try to be precise with their neck tension when they get around to loading the cases. To avoid this issue you have with the Lee trimmer, you'll need to get a larger expander ball or a smaller pilot for your trimmer to accommodate this spring back, depending on what you're trying to accomplish.
The 140°F temperature doesn't do anything to the brass . . . unless it's left at the temperature for many many hours, then it will have some level of annealing to have taken place (made a little softer).
Of course, if you're not already aware, brass will expand or contract depending on it's temperature, where the brass will be larger or smaller depending on its temperature. But, to be able to measure the change in size, there has to be quite a large variance between a cold temperature and hot temperature.
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You should be annealing. This one added step will almost assuredly solve your issue. It will take more than 140˚ to accomplish annealing. You will now enter a new and much deeper rabbit hole and Rod Serling will be your guide.
Thanks. That makes more sense than the 140 degrees affecting the shape.
That's next on my time-suck list. I've gone as far as trying to anneal by rotating in a cordless drill with a propane torch, but it did not seem to make much difference.
Are you sure you aren’t hitting friction? Wet cleaned/dried brass can get sticky. I tried wet cleaning for a while and found it to be a PITA/time consuming. Drying is already an extra step and then when I needed to add a dry lube step to undo the problem the wet cleaning created it became more trouble than it was worth.
