Annealing question

[dcali]

The color is the result of surface oxidation, not metallurgical change. You can ignore it.

 

[Ccrider]

Interesting thread. I have constantly noticed that my Es is lower after annealing. This is with all three of my guns. May just be coincidence but I don’t think so.

 

[JimSC]

I anneal after every firing but it is just one cog in the gear box and I am not 100% sure how effective it is in the big scheme. I can take cases from the same storage bin all prepped identically at the same time and and get single digit SD's or high 20's depending on the powder the load and the seating depth. I have been lazy at times and not annealed for a firing or two and seen no change in groups sizes, but maybe my skills and equipment are not enough to discern any difference. Put a custom gun in the hands of a .1 shooter and you may see a difference.

 

[Richard Coody]

my error. Meant to type increased

well that kind of depends on if you use a bushing die or a full length die with an expander ball. the springback will be towards the direction force was applied.

 

[Webster]

I just annealed my first few cases using 2 torches and 750 degree tempilaq on the inside of the neck. Exposed to heat until the tempilaq turned clear and then removed. Usually about 4 seconds. I did not get the discoloration on the case that new brass comes with. Am I overthinking or do I need to keep in heat longer?

You can get strange colors from very small amounts of stuff like case lube remaining after wiping with a paper towel. Looks like it might be a lot of heat based on how far the color comes down the neck with intensity??? Anneal in a dark room and look for any hint of red on the neck. The end of the neck turns red first. You may be OK. Doesn't hurt to check. The Tempilaq is saying your safe. I anneal with one torch and can get the tip of the neck starting to get red in 6-7 seconds. The tip gets red then the rest of the neck. Heat applied depends on the part of the flame touching the case. The bright blue pencil like pointed tip area is the hottest part of the flame. Use 0000 steel wool on the neck and shoulder area of a few cases, then wipe with a solvent that doesn't leave residue and see if you get less color change. If I tumble a case and it's bright and clean I get very little color change on the brass. Assuming the case is very clean the color is directly related to the copper oxide thickness which is time and temp related.

Not sure what you can do with the following chart but it shows color VS thickness of the oxide, assuming the surface is completly free from chemical films.

SOURCE: Copper.ORG
The colors formed on copper as a function of thickness, from Constable, Proc. Royal Soc. A, vol. 117, pages 376+ (1928) and Miley, Nature, vol. 139, p. 283+ (1937):
color thickness
Dark-brown 370-380 Å
Red brown 410-420 Å
Dark purple 450-560 Å
Dark violet 480-485 Å
Dark blue 500-520 Å
Pale blue-green 830 Å
Pale silver-green 880 Å
Yellowish-green 940 Å
Yellow 980 Å
'old gold' 1100 Å
Orange 1170-1200 Å
Red 1240-1260 Å

 

[Richard Coody]

These were all annealed the same. The 3 cartridges on the right had been tumbled recently. The rest it had been a while and you can see the distinct rainbow color from the transition.

View attachment 1056277

well i have annealed 1000's of cases with my geraud annealer and never had any that dark. possibly you have over annealed. i have done it before. an easy but destructive test is quite simple. take a new piece of lapua brass and a pair of pliers and squeeze the neck of that new brass taking note of the force required to crush the neck. now do the same to your annealed brass and compare.

here is a good read on annealing
http://www.6mmbr.com/annealing.html

 

[jepp2]

well i have annealed 1000's of cases with my geraud annealer and never had any that dark

And how about these?

 

[Drolds72]

somebody made the comment that since they have had 8-10 firings and have never been annealed, it might take a couple of cycles for better consistency. So I am going to take the same 25 that I did the first time and do it again. Had one of my kids time the flip that I did based on the tempilaq, and I might use a metronome set at 14 bpm to time myself with.

 

[Drolds72]

Ok. Just annealed the same 25 pieces after one annealing/firing cycle and answered my own original question. I did not clean the brass this time, and as mentioned several times, with the oxidation on the brass, I got a nice little color line on the brass. I also used a metronome to time the exposure and that worked pretty slick. Will find out Monday night if second time is a charm!