Re: annealing
If you keep case neck in flame long enough to heat head to 450F I believe the neck will be bright red long before the head gets hot which at any case you have ruined it.
Took some looking and here is response I did a few weeks back on same subject.
When I worked for the Army Small Cal Lab I had a friend down in Ammo Engineering who transferred to Picatinny from Frankford Arsenal when it closed and he was not only a ammo designer but a high power shooter of many years experience. His name was Marty Tyska who is now on the big range up yonder.
I had always heard annealing, dump in water, etc etc so I asked what he did for his cases.
I was already aware of how Frankford ran the production cases down a chute between gas flames while they rotated as they moved along as the Chief of the Small Cal Lab had been an ammo engineer at Frankford as well and he had told me they ran down the line and dropped them in a buggy. <span style="text-decoration: underline">I specifically asked him if they were dropped into water and he said "NO".</span> No one in the ammunition production industry dumps their cases in water as there is no need. Once the heat is removed from the neck/shoulder area there is no reason to think or assume the same level of heat will travel towards the head.
Marty said the best he came up with was to use a jewelers alcohol lamp and rotate the cases in the fingers while rotating the neck in the flames. He also explained to have the flame on the case body/shoulder and NOT THE NECK as he said the heat will run to the thinnest section first. I have on a number of occasions picked up a case I just "stress relieved" <span style="text-decoration: underline">by grasping at the head and do not get burned.</span> See temps below to determine how hot a case head gets.
He was very careful to explain you don't want them to turn them red as that completely annealed the case and all you need to do was stress relieve them.
He rotated them in his fingers and said "Your fingers will tell you when it is time to let it go." I bought the jewelers alcohol lamps (one for a spare) and this worked for years but had drawbacks. It had to be stored in a airtight container as alcohol would evaporate out. Then the druggies started buying it to make whatever they make and it went from 2.50 a gallon to about 18.00 so the alcohol lamp and my alcohol stove won't be used again.
The biggest drawback was it was S L O W ! ! ! ! I could do maybe three cases per minute rotating in fingers and this worked fine.
A number of years ago I read an article complete with SEM photographs of case grain structure that was "normal" and structure that was "ruined" due to too much heat. This article was in Precision Shooting and I sent it to Suasponte who has sent it to many folks.( he has that exotic high speed and I got Ma Bell)
This article has a complete explanation of how too much heat ruins cases. It was written by a metallurgist and I had another metallurgist who is also a shooter review his article and he concurred it was the correct dope. I also called the Copper/Bronze Institute and asked them about dunking hot cases in water and they said "NO".
Then about five or six years ago I was surfing 6br.com and found the case holders made on a lathe and the judicious use of a propane torch really speeded things up.
These exotic little holders are made from 3/4" round stock about three inches long. On one end turn it down to 3/8" about 1" long.
Remove the round piece and switch ends. Run 1/2" drill into other end and check occasionally while it is being drilled with a 308 case if you are going to load 308 and stop with about 1/4" of the case body still sticking out front. Note: you can do longer cases in these and they will of course stick out longer but assuming you have good holding ability you can use a 308 holder for 270,280,30.06,35 Whelen.
For 5.56 cases I use much small round stock just big enough to be drilled out and hold a 5.56 case.
This method is far superior to holding cases in fingers as with the drill held in both hands you can precisely aim the small inner flame at the area just below the shoulder and keep it right there.
I went to Home Depot and bought the smallest Burnzomatic tip I could get and READ THIS CLOSELY the green (short/fat) Coleman propane fuel bottles. Do not get the long thin tanks as they fall over very easily and it is a structure fire waiting to happen. The short/fat ones are perfect and provide a sturdy platform for the torch head.
I adjust the flame until the INNER bright blue sharp point flame is about 1" long(torch barely on).
Placing holder in variable speed drill I place case in holder and with bottom of drill on my stomach for support I tilt the drill over until the SHARP POINT FLAME is just touching the case at the lowest exposed point with the drill turning about 200 rpm. (I have a RPM counter and drill is a scosh faster than just turning.) My old Sears drill can be locked at a given speed so as to not get my trigger finger overstressed.
With the small blue flame contacting the case at the lowest exposed point I start to count estimated one second counts and at end of a count to 6 (30 cal cases) I pull the case neck back through the flame for perhaps 1/2 second, point drill down and drop it on towel. This used to be a old T shirt but I found a nice big white towel in the road the other day and will now upgrade to it since it has been washed.
The term "pulling back through flame" may be confusing and I will try and elaborate. The spinning case is rotated down onto the flame vertically and count is started. At the end of the count I just rock back slightly passing the rest the neck through the flame for no longer than 1/2 SECOND. If you find the area below the case mouth to be more bluish than the actual case mouth so "pulling it through the flame" on the way out gives it a even bluish tint.
Oh by the way ignition temp of cotton is 482F and I haven't ever ignited a cotton T shirt or sweat shirt.
When the case hits the towel you can see it turn blue on the shoulder/neck. I use a LC Match case as a temperature color gage. If the blue is brighter I did not do it long enough. If it is darker it was a bit too long.
<span style="text-decoration: underline">Contrary to popular belief the high heat does not continue down the case body to the head after being removed from flame.</span> Yes if you wait a few seconds it will get hot enough that you don't want to pick it up but no where near the heat level generated by the case during firing. As the case hits the towel you can actually reach down and pick it up (anyone want to guess which end to grab??) and toss it to another area and not get burned. Again no need to drop in water! ! !
How hot does a case get upon firing? A 5.56 case is approximately 170 degrees when ejected by AR and how is this determined? Take a trash can liner bag (PVC) and place it on the ground and eject your 5.56 cases onto the bag. The melting point of PVC is 176 deg F. I believe you will find the cases will deform the bag just short of the melting point and the PVC will not stick to the bag. A google search says Third Degree burns occur about 155-160 degrees F on most folks at one second exposure. The threshold of pain temperature is about 130 deg F.
Thusly if you pick up brass just dumped out and you drop it and don't experience burns then the case head is less than 130.
So we have:
Pain at 130F
3rd Degree burn at 155F
Case ejection temp on 5.56 approximatley 170F
PVC Melt point 176F.
I do not use gloves in this operation and assuming you are coordinated there is no reason to touch the case holder which of course gets heated every ten seconds and it will get hot.
Recently I have started stress relieving the cases as they come out of the Thumlers Tumbler after separating the media I have a pan full of wet cases in need of drying.
I have started coming in and stress relieving the necks with the remaining water here and there inside/outside the cases. If there is water up around the shoulder area I see it turn to steam and evaporate. I pick up cases after doing this and still find water droplets inside the cases and primer pockets. Logically if the water is still present in the primer pocket the 450 F stress relieving heat has not traveled to the case head.
Dumping all the cases in a pile creates its own heat so to speak and this residual heat helps dry the cases shortening the drying time in the sun or on the black plastic outside. I use black vinyl PE sheeting in summer time for a cheap heat source for drying. Dump cases on it and let the sun heat the PVC and dry the cases at the same time. I also have a nylon mesh clothing storage bag from REI I put a couple hundred wet cases in and lay over heat outlet(from floor) over night.
Now that I have a nice big towel, I will take them out and expose them to the sun.
As some of us know there is no prettier sight than a pile of newly cleaned shiney brass from the Thumlers Mod B with the perfect blue tint on the necks/shoulders gleaming in the sun.
