Necking up or down - once fired brass?

[omega1]

Hello everyone. I've been reloading 42 years but I've been following some recommendations without ever testing them. I was told that you should never neck size up or down cases that have been once fired. Is it true that only virgin brass is suitable to resize the neck? I'm mostly interested in .308 Win. to .260. I have a ton of .308 but shoot .260 and .260 AI more often.
Thanks

 

[dmoran]

Anneal and then size/expand away..... is my 2-Cents

 

[RegionRat]

Omega1, just goes to show you how unfiltered things can be in the open Internet forums...

The idea that you can’t size once fired brass is wrong because it doesn’t set a limit on the dimensions, and since the significant majority of all brass being reloaded is typically once fired, it sounds almost silly.

There can always be extreme wild exceptions and I would never say never, but lets say that the face value statement is false unless they explain under how much strain without annealing they are discussing. If you saw the raw form of the cartridge brass slugs we start with, you would known how silly that premise sounds.

Cartridge brass has limits like all other materials, but one of the best things about it is that it lends itself to use in cartridges very well. The engineering dimensions of stress and strain within brass include the concepts of tensile strength and ultimate strength, as well as the respective modulus for each dimension. When the brass gets work hardened, the modulus is stable but the ultimate tensile strength and several other properties change.

It takes specific cartridge and chamber dimensions to say exactly how much you can cycle a given design, but I can safely say that the number is much higher than one cycle, even if we are discussing a wildcat design.

If you can find those references where those claims were made, maybe we can clarify them or refute them, but in general that isn’t anything to worry about. You can grab your own once fired or even buy once fired and get going on your loading developments. If you get into extreme wildcat loads, you will typically know when to anneal.

 

[Bill K]

I have been necking them up and down for a long time. Often it is good to anneal them first, but I have also done it without annealing at the time.

 

[omega1]

Thanks for the replies.

 

[Zero333]

Decades ago not many people annealed, so new brass was best for necking up/down. Nowadays you can have brass fired multiple times and as long as you anneal it before necking up/down there is no problem.
Also even with new brass, if you're sizing the neck in 2 steps, it might be good to anneal between the steps.

As a side note... when you neck down, it's common to have to turn the necks cause they will be thicker than before.

 

[Zero333]

Forgot to mention... going from 308win to 260rem, go down to 7mm first if possible.
It also depends on the brass you'll be using. Some brands are easier to neck down than others.

 

[riflewoman]

Hello everyone. I've been reloading 42 years but I've been following some recommendations without ever testing them. I was told that you should never neck size up or down cases that have been once fired. Is it true that only virgin brass is suitable to resize the neck? I'm mostly interested in .308 Win. to .260. I have a ton of .308 but shoot .260 and .260 AI more often.
Thanks

Posh! Do it all the time.

 

[Ledd Slinger]

Hello everyone. I've been reloading 42 years but I've been following some recommendations without ever testing them. I was told that you should never neck size up or down cases that have been once fired. Is it true that only virgin brass is suitable to resize the neck? I'm mostly interested in .308 Win. to .260. I have a ton of .308 but shoot .260 and .260 AI more often.
Thanks

Never heard anything about not using once fired brass before...

But it's better to neck DOWN than it is to neck UP if you can.
The shoulder area in brass is thicker than the neck portion and can cause donuts at the base of the neck when expanding the neck up in size. Of course going up one caliber from something like 7mm to 308, or maybe 224 to 243 isnt really going to have any significant negative effects, but necking up 2 calibers or more can be troublesome for donut formations in the brass.

Definitely step the 308 down to 7mm before going to 264 as suggested above. Ive done it before when making 6XC brass from 308 cases. (308 all the way down to 243)

Just get a 7mm-08 FL die. Run the 308 case in the 7mm-08 die, then lastly in the 260 die. Also as suggested above, you will more than likely have to turn the necks as the walls will be quite thick after necking down that far. Other than that you'll be good to go

If making 260 AI cases, run the 308 case "short" in the 7mm-08 die, maybe 3/4 the way down the neck. Might have to go a little further, just need to play with it.
Then run the case in the 260 AI die to neck down the rest of the way and bump the shoulder to the AI configuration. This will set a nice false shoulder so the case seals the chamber good during firing.

 

[farmerjohn]

Forgot to mention... going from 308win to 260rem, go down to 7mm first if possible.
It also depends on the brass you'll be using. Some brands are easier to neck down than others.

+1, on both of Zero333's last two post, been doing it for years. Doing it with two steps does make it a lot easier. Imperial die sizing wax also...

 

[LCazador]

Obviously the once fired brass you're going to neckdown was fired in another chamber. You should start with knowing the dimension of the chamber you are necking down to. You should then neck down with a bushing full length sizer and work your way down incrementally by first sizing down to 290, then 277, and then to 264. This incremental sizing not only prevents crushing of the brass but also allows for much straighter and concentric piece of brass. You will also need to trim all your brass before it's fired in the new chamber. Sizing down or working the brass will make the length inconsistent. It's a lot of work. You would save time by just buying new 260 brass but then it's a good project when it's snowing outside and you're looking for something to do indoors!!

 

[NorCalMikie]

Best to try one or two to see if the brass is too hard OR too soft. Annealing can make the brass too soft to change. You'll know the first time you crush the shoulders down into the body. A split neck will also be a good indicator.

 

[Walt Schmidlin]

Would not recommend trying to make 260 Rem brass from military .308W/7.62 brass. Tried to make 7/08 brass from LC Match brass fired in “match” chamber, required significant neck turning in order to chamber in a factory M700 chamber.
Assume trying to go to 260 Rem from military brass would be too much work, not worth the effort.