Necking down from a 300wsm to 270 wsm

[10point]

What is the value of necking down a case? Is the necked down version a stronger case that allows greater pressure without greater danger?

 

[J E Custom]

What is the value of necking down a case? Is the necked down version a stronger case that allows greater pressure without greater danger?

Their may be a small amount of neck thickening .0005 to .001 but not enough to cause problems
just the same you need to mic. the necks before and after to make sure that they will still fit in the chamber loaded and with at least .003 clearance when loaded.

If you size the 300 WSM brass use your 270 dies. you will also see a small donut at the base of
neck about .022 from the shoulder. (This is corectly sized and will fire form fine).

I personaly prefer using a larger case and sizing down than sizing up a smaller case.

J E CUSTOM

 

[10point]

Does the neck thickening allow slightly more neck turning thereby getting a more uniform neck thickness?

 

[Lefty7mmstw]

Necking one case of a family to another has more to do with component sourcing than anything else. You don't get brass that can take more abuse. They pretty much all will take the 65,000 psi saami allows them.

The only time you will benefit at all is if you take one of the brands that last longer( lapua comes to mind) and re-form to another caliber.

Necking and forming brass takes some care also, as you don't always end up with a square product. Brass tends to grow differently on one side than the other. I've taken this to the extreme trying to knock the neck out of an '06 necked to 35 whelen. I took it from 35 whelen to 270 win three times and measured the length disparity between sides of the mouth. The high side was 40 thousandths taller than the low side. That is a lot of difference in neck thickness between the high and low sides.

 

[10point]

Thanks, That is the answere. If there is a shortage or a better brass then necking down is a good option. Otherwise stay with the caliber of your gun.