Forming7/08 brass

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haffordite2

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Given that 7/08 brass is a scarce commodity (at least in my area), I tried reforming 243 into 7/08 using the 7 mm sizing die. 243 brass was run into the 7mm die, opened up and full length resized. Reforming seemed to go alright but reformed brass won't chamber. Obviously something is not right shoulderwise. I tried necking down 308 brass (knowing the necks would need to be reamed) with the same result. While I am no newbie to reloading, obviously I am doing something wrong. Other posters say they had no difficulty forming 7 mm brass so my question is what am I doing wrong? I would appreciate any suggestions especially from those that have actually reformed brass.
Thanks
 
I would think that measuring and comparing a piece of factory 7-08 brass would likely reveal the problem.

However I would guess it has to do with the brass "springing back" and annealing may solve it.
 
Hmmm....that is weird, other than having to lube up the inside of the neck real good so you don't get the mandrel stuck it shouldn't create an issue. I belive the nominal distance to the shoulder is the same for those cartridges. Only thing I have is you pulled the shoulder out on the upstoke. The .308 stuff should be a no brainer. What kind of 7/08 die are you running? Possible something could be off there with the setup I suppose...
 
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r204 said:
try running the brass through the FL dies a couple more times and see if they will chamber after that
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When forming cases from "used" brass, this can be a real issue. If you don't know how to anneal brass, here is how to do it easily and quickly.

Heat up your oven to 500+F, or as hot as it will go. Take a cake pan and put about an inch of water into it. Then take your decapped cases and set them on their bases so the case mouth is up and out of the water.

When the oven is at its max temperature, very carefully place the pan of water and brass into it, without tipping the brass.

Leave it there for about 10 minutes. The water should be boiling or close to it by then.

While this is going on, fill up the sink or have a half bucket of cold water on hand to dump the contents of the cake pan into.

This won't make the brass dead soft but it will definitely take most of the hardness out of it.

This will take away the tendency of the brass to "spring" back.

One other thing. Don't be afraid to set the shoulder back a bit more than what is called for. Your first round of shooting will fire form it to your chamber anyway. Trim the overall length of the case to minimum spec.

DON'T ream or thin the necks. That is an old wives tale and does nothing for accuracy unless you have an extremely tight match chamber. Also, it doesn't thicken the neck enough to be noticed. Maybe .00001 at most. If you have an off the shelf rifle, it won't even notice.

I suspect, you aren't setting back the shoulder enough or your case neck is to long. When sizing down case necks tend to stretch, rather than compress. The brass has to go somewhere.

I always fire form with mid range loads or close to what I want to load to. That makes for high enough pressures to iron out all the kinks and mate those cases to your chambers. Some folks like to use corn meal or some such over the powder charge. This usually doesn't give satisfactory results and means you have to fire form twice.

Some guys use cast lead. That works OK. I use the same bullets I intend to hunt with. Makes for an early stage in load development. Saves time and money in the long run.
 
Bearhunter....great recipe for annealing the brass. I just finished goggling a bunch of stuff and said the hey with it. But your technique is simple and a guy can do a bunch of rounds at one time. My question is if using new 308 brass should they be annealed? And do you do if first before FL resize or after? The other question I have is if the water is boiling, is there concern that you're softening the head?
 
waynewjw said:
Bearhunter....great recipe for annealing the brass. I just finished goggling a bunch of stuff and said the hey with it. But your technique is simple and a guy can do a bunch of rounds at one time. My question is if using new 308 brass should they be annealed? And do you do if first before FL resize or after? The other question I have is if the water is boiling, is there concern that you're softening the head?
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New brass is dead soft already. No need to anneal.

Size it in the 7-08 die with the expander ball in place.

Lube the full length of the case and the inside of the neck.

Trim the overall length to minimum specs. Make up a dummy cartridge, without powder or primer but a bullet seated to the length you want it to be. It should feed and chamber easily.

If you have a very tight chamber, you might need a set of small base dies.
 
I own two 7mm-08 rifles and I don't own a piece of brass that says 7mm-08 on the head. It is all used 308 bras that I simply sized and deprimed in my rcbs 7mm-08 dies. Not once have I had trouble with anything.
 
See the following articles regarding oven annealing before attempting.

Changes start to occur in brass grain structure at 480 degrees fahrenheit. To properly anneal brass, the temperature needs to be at 650 degrees F. for several minutes--BUT this will transfer too-much heat to the lower case in that time. So we need more heat for a shorter time. We need to raise the neck temp to about 750 degrees F. only for a few seconds to anneal.

Source:
http://www.annealingmachines.com/how-to-anneal.html
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Exactly how much and when this happens depends on the material, the temperature applied, and the time that temperature has to act on the metal. For cartridge brass, the transformation is rapid, robust, and occurs at approximately 650-700 degrees Fahrenheit. If you apply a higher temperature, the brass will get even softer, but not dramatically so.

So is it possible to over-anneal case necks? Yes. But it's not quite as touchy of an issue as various internet message boards might have you believe. But there is no reason to heat brass beyond 700 degrees Fahrenheit - the desired effect has been achieved at that point.

It is critical to understand that we are talking about annealing case necks only. The rest of the case is work hardened during manufacturing and left that way on purpose. It must be strong enough to contain the pressures of firing, and annealing any part of the case except the neck is potentially dangerous. Do not do it. Under no circumstances should you let the case body get anywhere near 700 degrees. If you do, the case is ruined, and should be crushed and discarded. You cannot anneal brass in an oven! You will ruin it.

Source:
http://bisonballistics.com/articles/the-science-of-cartridge-brass-annealing
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Optimal Case Temperatures for Successful Annealing
Brass is an excellent conductor of heat. A flame applied at any point on a case for a short time will cause the rest of the case to heat very quickly. There are several temperatures at which brass is affected. Also, the time the brass remains at a given temperature will have an effect. Brass which has been "work hardened" (sometimes referred to as "cold worked") is unaffected by temperatures (Fahrenheit) up to 482 degrees (F) regardless of the time it is left at this temperature. At about 495 degrees (F) some changes in grain structure begins to occur, although the brass remains about as hard as before--it would take a laboratory analysis to see the changes that take place at this temperature.

The trick is to heat the neck just to the point where the grain structure becomes sufficiently large enough to give the case a springy property, leaving the body changed but little, and the head of the case virtually unchanged.

If cases are heated to about 600 degrees (F) for one hour, they will be thoroughly annealed--head and body included. That is, they will be ruined. (For a temperature comparison, pure lead melts at 621.3 degrees F).

The critical time and temperature at which the grain structure reforms into something suitable for case necks is 662 degrees (F) for some 15 minutes. A higher temperature, say from 750 to 800 degrees, will do the same job in a few seconds. If brass is allowed to reach temperatures higher than this (regardless of the time), it will be made irretrievably and irrevocably too soft.

Source:
http://www.6mmbr.com/annealing.html
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I form brass all the time, you can't believe any case head stamp in my loading room, and I have never had your problem..........what make of dies are you using? Are you setting up with a good cam over bump on the sizing stroke? I have made every caliber available on the 308 case from 308 brass, even using military brass and have never encountered your problems. I have also never found it necessary to anneal cases to form, using 308 or any 308 based case, not even military. I much prefer to go down in neck size rather than up and although I have 7-08 brass, I use it for 260 and made 7-08 from a bunch of new W-W 308 cases I picked up a while back. If going up is necessary I prefer to make an expanding mandrel and take it up slowly over the mandrel to a caliber or two over size and then run it through the FL sizer die for final forming. OR if it headspaces correctly as all 308 based cartridges do, I just load them with some excess bullets in original caliber and fireform them in the larger caliber chamber.....loaded 308 becomes 358 Win instantly, and your 243 would become 7-08 just as easily. This method produces more concentric necks, by far, than necking up in stages with dies or even on a nice slow tapered mandrel, and is my preferred method of up sizing cases. In fact just did 60 300 WM to 375 Imposter the other day.......works flawlessly.
 
Thanks for all help and suggestions. I annealed the cases I had already formed, FL resized them ( twice) stuck a reclaimed bullet on one and tried it. Chambered Ok. Added powder and bullets and fireformed the rest. Everything seems OK-necks from 243 are a bit thin but a light crimp with my Lee crimp die stabilized bullets. My RCBS junior press seems a little light for necking down 308. Need a press with compound leverage so I will stay with necking up 243 for time being. Thanks again
 
I have a junior press and I have sized and formed .308 cases for years. I am happy to hear that you had some success with annealing, but it still sounds like a lot of work that is not usually necessary.
For what it is worth, I make my 7mm-08 cases from .308 cases. I use a .308 FL sizing die first. Then I run the case through the 7mm die to size down the neck.
If you are having problems, I would suggest that you are not using enough case lube, or the right type. And cam over on the press should result in the die touching the shell holder. You don't need compound leverage press to do this.
 
I just tried this yesterday.
Some range pick up .243, ran the first case through my Hornady FL die and the case neck split. I tried 2 more pieces of differing headstamps and they split too.

I threw in my old RCBS FL die, and voila, 3 perfectly formed pieces of Rem, Win, and Fed brass, which all chambered in 2 different 7-08's.

Go figure!
 
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