wheelgun7360
Silver $$ Contributor
Annealing Technique
- Thread starter wheelgun7360
- Start date
jepp2
Gold $$ Contributor
Was the Starline brass new? If so it was annealed prior to being shipped.
Certainly not an expert. The visual appearance of annealing varies GREATLY depending on the normal oxidation the brass has undergone prior to annealing and the time that has passed since annealing.
What temperature did you anneal these? The color change appears to be in the correct location.
I've been playing around some with stress relieving (done with the brass reaching 750 degrees F) and annealing (done with the brass reaching just over 1000 degrees F). For brass that has a similar patina prior to annealing, you cannot tell which were done at either temperature. They look identical. That is why it is so difficult by the appearance of the brass to determine if they were annealed correctly.
To me these always looked like they might have been annealed at a slightly high temperature. But for the reasons I mentioned, no way to know. They are factory rounds from the Lake City munitions plant, so I would probably pick the bet they were done correctly.
Certainly not an expert. The visual appearance of annealing varies GREATLY depending on the normal oxidation the brass has undergone prior to annealing and the time that has passed since annealing.
What temperature did you anneal these? The color change appears to be in the correct location.
I've been playing around some with stress relieving (done with the brass reaching 750 degrees F) and annealing (done with the brass reaching just over 1000 degrees F). For brass that has a similar patina prior to annealing, you cannot tell which were done at either temperature. They look identical. That is why it is so difficult by the appearance of the brass to determine if they were annealed correctly.
To me these always looked like they might have been annealed at a slightly high temperature. But for the reasons I mentioned, no way to know. They are factory rounds from the Lake City munitions plant, so I would probably pick the bet they were done correctly.
CaptainMal
Silver $$ Contributor
Add the word "properly" to the post above and I second that statement.
If you saw a slight reddish change in color when the machine turned out of the flames you are probably correct if the reddish color was "slight". I mean if you just think it is turning ... that is enough. If it is noticeably red ... too much.
If you saw a slight reddish change in color when the machine turned out of the flames you are probably correct if the reddish color was "slight". I mean if you just think it is turning ... that is enough. If it is noticeably red ... too much.
wheelgun7360
Silver $$ Contributor
Brass was new but did not look like they were ever annealed from Starline!! Brass never turned red!!
Squeeze the neck on one of the cases with your fingers our pliers. If it has little resistance to being deformed a little oval I would say they got to hot. Sacrifice a scrap case anneal it bright red a see how little stiffness the neck has. If the necks have decent stiffness I would say your OK. I know a lot about annealing but I lost my ability to do hardness testing when I retired. I use a standard handheld propane torch. I used to anneal about 9 seconds which is a little below red. I got tired of seeing the ends of the neck sometimes getting red so I reduced the time to 5 seconds. Probably not annealing but stress relieving. Don't care if it doesn't meet some ones requirement for more heat. The necks are very firm and I have over 20 reloads on my brass. Even at 10 seconds I never got any where near the degree of dark color you have. Factory annealed brass is probably cleaned after annealiing. The color isn't always copper oxide. If there is any lube or cleaning chemical residue on the brass it can have a big affect on the color. Steel wool a few cases and clean only with water or alcohol and see if you get a different appearance. The neck end tips turn red a few seconds before the bulk of the neck. Red is about 1050F. If the tips are starting to turn red I would back off maybe 1 second. For most of us I don't think we will ever see a difference in accuracy regardless what the annealed hardness is. My varmint hunting 6BR shoots any load under .400". Even at 10 seconds I was getting very little color change.
I pretty much agree with what the posters above have said. Just speaking for my self but I have never seen that much heat oxidation.
High temperatures are causes the rainbow effect of the metal. Higher temperatures lead to faster oxide growth and thicker layers of oxide. When light passes through the layer it reflects off the metal but some is also reflected from the oxide. When the oxide forms to a certain thickness, interference between the two can occur and the rainbow effect happens. The color is dependent on the thickness and the thickness on the temperature so there is a continuously changing color of the rainbow effect, just like light in a rainbow in the sky. Chemicals on the brass can cause a increase in this oxide formation.
I try and make sure my brass is very clean before annealing with no oily residue. Any chemical residue on the brass can also cause thicker oxide layers so the rainbow effect cannot be used as a indicator.
I used to wet clean with dish detergent and would have to do a multiple rinses to get rid of all the suds, now I just use a Cascade dishwasher tab and found multiple rinses are unnecessary. I have no suds and no residue is left on the cases. A single rinse is all that is needed. Since going to that method of cleaning I have noticed the oxidation rainbow is minimal. I now anneal after every firing on a Annealeeze and have noticed a reduction in uncalled flyers and more consistent velocity SD and ES numbers
High temperatures are causes the rainbow effect of the metal. Higher temperatures lead to faster oxide growth and thicker layers of oxide. When light passes through the layer it reflects off the metal but some is also reflected from the oxide. When the oxide forms to a certain thickness, interference between the two can occur and the rainbow effect happens. The color is dependent on the thickness and the thickness on the temperature so there is a continuously changing color of the rainbow effect, just like light in a rainbow in the sky. Chemicals on the brass can cause a increase in this oxide formation.
I try and make sure my brass is very clean before annealing with no oily residue. Any chemical residue on the brass can also cause thicker oxide layers so the rainbow effect cannot be used as a indicator.
I used to wet clean with dish detergent and would have to do a multiple rinses to get rid of all the suds, now I just use a Cascade dishwasher tab and found multiple rinses are unnecessary. I have no suds and no residue is left on the cases. A single rinse is all that is needed. Since going to that method of cleaning I have noticed the oxidation rainbow is minimal. I now anneal after every firing on a Annealeeze and have noticed a reduction in uncalled flyers and more consistent velocity SD and ES numbers
NorCalMikie
Gold $$ Contributor
And if annealed "again" from new, could be an issue with necks being pushed down into the case body when seating the bullet. 
You learn that when building wildcat rounds.
You learn that when building wildcat rounds.
Coyotefurharvester
Silver $$ Contributor
Norcal is correct.
Don't know if you needed to soften them any prior to necking up, sometimes that creates problems. You need to try necking up without re-annealing and see if you get any cracked necks. I am sure that you need to re-anneal after necking up. I learned that the hard way.
Don't have near the experience that some of you guys have but I have necked up from 6.5 to .30, down from .30 to 6.5, and from 6.5 to 6 while moving the shoulder back and in every scenario found it was better to wait until after the resizing to anneal. Like Norcal said , when I annealed first I had problems just like he described
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