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Annealing 30/06 Rifle Cases
Annealing Cases
I had some 30/06 Federal Gold Medal Match Cases, with 4 firings that I wanted to use with my new rifle. The advantage over new brass is that they have already been fired in a chamber which was cut with a reamer from the same manufacturer. This means I wont have to develop a new case load and then a slightly different used case load. The cases tend to have a bigger volume after firing even when full length sized. At about 4 - 5 firings in a 30/06 (7 or 8 in a .308) the shoulder bump or full length sizing operation starts to get less responsive as the brass has work hardened a bit and is starting to get what I call springy. It springs back after a shoulder bump to its original size that is too big to fit in the chamber unless you lower the die some more. Neck sized cases will start to show flyers after this many firings; the bolt will start to close hard on some of the cases. Time for new cases or an annealing step. The annealing step softens the brass.
I have tried annealing cases previously without much luck. Here is a method that I found that works to my satisfaction. The major goal for me is to have very uniform brass. If you try heating the cases without rotation even with two torches it is going to heat unevenly. One case may not be like the next. Then it will form to a different size in your full length die or shoulder bump die. If you rotate the case with an electric screw driver, your chances of getting a uniformly annealed case are much better. Photo 2 shows the electric screw driver and the K & M Case Holder which takes standard reloading press shell holders. Tighten the case holder by hand just tight enough to hold the case. No tools needed
A Lee case holder from the Lee neck trimmer will work as well.
What Temperature, How Long?
Hornady sells an annealing kit part # 41220 with 475 F Tempilaq paint. This paint is applied and is opaque. It clears up at the proper temperature. I have also seen an article suggesting heating until the case just shows a blue color when hot and where the case keeps the shine when cool; if it gets dull red you have gone too far. Another temperature recommendation I have seen is 600-650 F. Others suggest heating until the necks show red. Still others darken the room and heat until it just shows red in the darkened room. Photo 3 shows a Lapua factory annealed case on the far left. They probably know something about annealing. The shine is gone, but there are no dark colors. Now how to achieve this with a propane torch.
I used a Benzomatic brand propane torch with the pointed flame tip installed. The tip has a large center hole as well as holes on the perimeter of the tip. My first attempt in a lit room is shown in photo 2. Too much darkened brass. I attribute this to the cases getting too hot. I tried to use a temperature gun on a glowing case, but this was hard to do, due to the cases small size. I got an out of range reading and one of about 460 F as my highest readings.
I practiced some more in a mostly darkened room and determined that over 9 seconds of heat was too much, less than 7 seconds was too little. I used the color of the brass of the cooled case as an indicator as well as the first hint of red over the area I wanted annealed. I compared the finished color to the Lapua case.
The point of the inner cone is the hottest part of the flame (see photo 1). I put the tip of this cone 1/8 inch left of the shoulder to body junction of the case. The shoulder is harder to heat than the neck as there is twice as much brass there on the bigger circumference. This position of the flame tip concentrates the heat on the shoulder and puts the neck in a cooler part of the flame; the neck starts to glow and the shoulder shortly after with this positioning. A dim glow like in photo 7 is all that is needed. Photo 8 and then Photo 1 shows the progression that occurs in the next two seconds. The temperature of the brass in photo 8 and 1 is too high and the neck will be discolored when cooled. Photo 4 shows some freshly annealed Federal necks. Note that the left hand case is a new Lapua case which is annealed at the factory and is placed there for comparison. My annealing is to an even length on the cases. The necks, although slightly darker than the bodies, still have some shine left to them when viewed with the eye. Photo 5 shows the same cases after vibratory cleaning. The stock (unpolished by me) Lapua Case is still on the left.
Photo 6 shows a set of Federal Gold Medal Match Cases that were neck turned on the Lathe, Fired 4 times and then annealed with the process above. I held the torch 1/8 inch left of the shoulder to body junction to reduce the heat on the necks a bit. I cleaned them a couple of extra hours in the vibratory case cleaner. They came out nice. Should work great in the tight neck chamber.
I cooled the case (and chuck when necessary) in a pot of water. Takes about 8 seconds of heating per case.
I did some more test with the temp gun. When the case is showing red with room lights on it is about 497 F. This is a little too hot for the brass. My gun overanges at 500F.
Do Not Anneal the Case Head
Varmint Al has an interesting finite element analysis he did of a 243 Winchester Case being fired with an annealed Head. Interesting figures of the case failure as well as data on the strength of soft and hard brass.
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Bob
Thanks for the note. I am alway interested in Feedback. Interesting about the army using used cases. I guess military once fired brass may not be only once fired. I read a couple of reports about using the lead bath. The temperature of the bath is around 600 to 650. I think the lead melts at about 600 F. Don't know how long the army leaves the cases in the bath, Probably timed and done with machinery, but for me I would likely get the case hotter than needed by not being able to monitor the brass color. I am also not setup to cast bullets and like to do the work indoors. I read one report where the guy dips the case in oil first and then uses the lead bath. This keeps the lead from sticking. The propane torch seems to be a lot heathier way to do it.
Tell me if you are willing to post your e-amil in my Journal. I'll post this answer there too if you do. Might be nice to have a discussion in the Journal. There are about 60 guys that look at it regularly. I always learn the most from Feedback and Discussions. -
Posted with pemission
John,
Recently got your book on rebarreling and loved it…very well written and photographed! Keep up the excellent work by all means.
Also, just read your annealing experiment and really enjoyed it. I have annealed a few times in the past but it was nowhere near as precise as what you did. I was forming 7.92x33 Kurz hulls from .308 Win and was annealing the cases before pushing the neck back a significant distance. I figured if the neck was going to be moved back almost an inch it might be better to have it softer to begin with! Must have worked as the necks all went back with no problems.
So far as what Lapua did to anneal their cases, the pictures you show look just like the discoloration which our US 5.56mm military ammo looks like. Most people do not know it (including soldiers, too) but I estimate over 90% of the ammo we use in the Army is reloaded from previous firings. It is not often that I shoot M16's where the ammo is not discolored from being annealed. Most troops never think about it, but after we range fire we always pick up the brass and turn it in to the local ammo supply point. In turn, they forward it through channels to the manufacturer for reloading.
I have heard (but cannot remember the source) that our arms factories anneal the old cases by dipping them in a lead bath to bring them up to temperature. They do not use flames. By doing so the exact height of the annealed area is precisely controlled and also the time to heat the cases is equally well known as the temp of the lead bath is easily measurable.
COL Bob Bishop, USAR
North Little Rock, AR
7/13/04 6:18 PM
Go ahead and post this in your journal...I would like one of your readers out there to add any more detail to this area if they know exactly what the big ammo makers actually do to anneal the cases. Remington's big ammo plant is only 20 minutes up the highway from me, but, they absolutely do not allow anyone into that place to see what they do to make the rounds. Proprietary information I guess.
It would be safe to assume that military "once fired brass" is not just fired once! Because a factory gets an order to produce X million rounds of ammo does not mean they must start out with virgin brass. Also, USGI brass is heavier in weight than equivalent commercial brass and for this reason all the reloading books advise to lower your maximum load by some amount to account for reduced case capacity.
I just came back from 14 months in Iraq and can tell you horror stories about how hard it is to keep your weapons clean over there. That &%$*&% dust/sand is literally everywhere and you must clean weapons at last twice a day during sandstorm season (Feb - May). During normal times you still clean them at least once every day.
During my time over there I did not see a single Iraqi ever clean their weapon. I saw literally thousands of firearms being used by them and NOT ONE cleaning kit in the slightest. They seem to just use their firearms until they jam and then get another new one. This can be done as their country is awash with arms and having at least one AK and pistol for each house is normal. Most homes have at least one AK for every male and a couple of pistols for good measure. Every 10 houses has a belt fed machinegun and at least one house in each block has a RPG available.
Bob