Sizing 260 brass to 243 risks

[ranger3]

I have decided to retire my 260 and have a hundred rounds of 260 brass Lapua brand that I would need to size to 243 am I running the risk of Donuts or anything else. My 243 out shoots my 260 so I'm trying to move in that direction. Would I want to run.them through a FL sizing die first before going to 243?

Thanks for your thoughts on this.

 

[Iowa Fox]

Just my thoughts which isn't much, I'd advertise the 260 brass here in the classifieds and repurchase some 243 brass

 

[dstoenner]

You will have thicker necks. When I sized some 308 brass to 260 I had to turn the necks a lot but once turned they were fine from then on. Also the case will be shorter than the normal trim length

David

 

[riflewoman]

Done that. Two things. In many instances the brass might need turning as necking down can lead to uneven neck thickness. Dunno til you try. Second, this adds cold work to the brass so if it has some firings might want to anneal before you do this.

 

[fyrewall]

You will probably need to turn the necks down. Going from an inside diameter of .264 to .243 isn't excessive but when finished the neck walls will be thicker. Thicker neck walls probably will increase pressures if bullets are jammed tight inside the chamber.

Before beginning I would anneal the brass to reduce differences in spring back from case to case and reduce differences in cold-working from piece to piece. After annealing I would run the cases through a .260 die with no expander button then through a .243 die with expander button then neck turn. Lapua brass is pricy. I never made .243's from .260's but have made .260's from .243's by fire-forming.

 

[ranger3]

Appreciate this advice, I have seen 308 sized to 260 and even 243. All needed neck turning. I don't want to get unsatisfactory results. I have sized 243 to 260 and back again without issues.

 

[mikeinct]

I've got a 100 lot of 243 win used brass, Lapua..I could trade you st8 up..Mike in ct

 

[ranger3]

My brass is once fired with a light load, I'm going to think about this for a while. I know someone who resize brass commercially see what he has to say. Will get back to you.