Brass Thickness - 308 family

J

JEC

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I have heard opposing views regarding comparative brass thickness between the different cartridges based on the 308 cartridge. Since this could be a reloading issue...would appreciate comment from someone who has the tools to actually measure..
I am resizing 308 Win down to 260 Rem .... does the 308 have thicker walls than the 260 Rem?
 
Not necessarily, but if you are using Military brass it will be thicker. Also anytime you neck down that much, the neck wall thickness will be a factor. Your newly-made 260 brass may require Reaming/turning to work properly in your 260 rifle. Regards, Eagleye.
 
My Winchester brand -- 260 Rem brass has an outside diameter of .290 when loaded.
My Federal brand -- 308 brass resized to 260 Rem has an outside diameter of .297 when loaded.

So, the walls of the resized brass must be .0035 thicker than the "factory" brass. Most of the groups I shot with the larger neck OD are pretty decent....under 1/2" @ 100M ... for a sporter style rifle.
However, most of the groups with the factory 260 brass are nearly as good.

I have fired the larger diameter cartridges without any signs of pressure. Is there any advantage to turn down the necks of the resized brass?
 
Hi

The real question is: What's the diameter of your rifle's chamber up by the neck?

As long as the brass is about 0.004" smaller than the chamber, you should be ok. Past that you run some risks in terms of pressure and chambering.

The max neck diameter on a .260 is .297", so your 308 brass is right at the maximum. I would turn it down a tad ....

Bob
 
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