necking Down 308 to 243

[Skinna]

G'day O' experienced ones.

As the title suggests.

I already neck down 308 to 7-08 without any trouble using Win brass.

The only thing i have to watch when doing this, is the thickness of the brass of the brand i use, as thicker brass has proven to give out the obvious pressure spikes from not being able to completely free the bullet.


So anyone done 308 > 243 in one pass...?
I cant see any harm in trying it, but Is it worth sizing the neck down to 7mm first...?--if so, is there any issues with the shoulder going from 308-243...?
(id assume not, but i shouldnt assume, hence the question).

So aside from the point of being cautious of pressure from thick brass, is there anything else i should beware of...?, &/or, any particular process you think is worth following.?

(Thinking of doing this with PPU brass because of price)

Thanks in advance.

[Bugman]

For the amount of usage my 243 gets, I just use new 243 brass and re-use. An interesting exercise though. I would be interested on how you get on if you go ahead.

[Blr243]

I tried it once It was not something that I just pushed the handle all the way down. Then was lots of up and down 2 or 3 mm at a time .......it was just an experiment when I found a 308 case in amongst some once fired 243 cases I bought .....I think an intermediary die would be crucial The overall length of the experimental case was significantly different than my factory made 243 cases ......it worked was a fair bit of messin round

[in2anity]

I've found necking down specifically PPU brass to be problematic. Splits yarda yarda.

[straightshooter]

I regularly resize Winchester and ADI 308 range brass in one pass with just a Lee FLS die.
The secret is the lube I use which is castor oil. It has the lowest co-efficient of friction between brass and steel of any lubricant.
You only need the really thinnest smear on the case and inside the neck.
The necks will need annealing but avoid letting the heat run into the shoulder.

[marksman]

l think you are going to have to just give it a go Skinna, l would be giving what SS said a go and neck turn for better uniformity

[TassieTiger]

I know it’s not the question but it might be relevant.
Before I started using purpose brass, I’d size 308 down to .260 in a single pass without too many issues. But - it did take a case or two setting up as you could see the brass flow into neck area. It’s a fair jump to .243.
Might be easier to buy a 308

[Blr243]

I have never paid close attention to alternative, possibly cheaper alternatives to commercial lube until now ...the way SS describes it I would be mad not to give it a try. My first google Search found 100 mls for 7 bucks so I’m onto it

[on_one_wheel]

I would have thought that given the abundance of used and new .243 brass, that necking down .308 brass wouldn't be worth while.

Imo, Your time would be better spent cleaning, preping and sorting used .243 brass.

[Skinna]

I would have thought that given the abundance of used and new .243 brass, that necking down .308 brass wouldn't be worth while.

Imo, Your time would be better spent cleaning, preping and sorting used .243 brass.

I dont really have access to any used brass, & the cost of new being 50 cents a pop is pretty attractive--new brass & rifle & the brass might last the barrel if not hammered too badly (or lost in the field).

Like i said in OP, i neck down Win 308 to 7-08 in one pass with FLS die & get a 1-2 thou bump with it--so its actually less work than having to fire all the cases twice before they are fully formed to chamber & dont have to turn necks.

So if i can get it done in one pass & not have to neck turn, i see it as a goer...Or if you can point me in the direction of this cheap abundance of once fired reasonable quality brass, ill be open to considering it as an obvious viable option.which is what im here asking--for opinions from those who may have done it or have other solutions.