7mm08 from 308

dirty habit · January 13, 2007, 03:43 PM

Hi, Just wondering if anybody out there knows how difficult or easy it is to form 7mm08 brass from 308? Is it a better idea to buy 7mm08 brass or reform?
Cheers

snuffy · January 13, 2007, 05:18 PM

It's as simple as lubing well, then running the .308 empty into your 7-08 full length sizing die. HOWEVER you will end up with a 7-08 casing that's shorter than a standard 7-08 by as much as .020. That's because the .308 is 2.015 and the 7-08 is 2.035 trim length.

In the real world, that's not enough to be worried about, there's still plenty of neck to properly grip a bullet. Another thing that CAN happen when necking down, is the neck becomes thicker. If you are dealing with a tightly cut match chamber, it could result in no room left for expansion of the neck during firing, even preventing chambering in a worse case scenario. A standard sloppy factory chamber probably won't know the difference.

Peter M. Eick · January 15, 2007, 04:57 PM

It is easy to do, but be careful to work up your loads carefully. The only blown rifle round I have fired was a 308 that ran though the 7-08 dies and was shot on a hot day. It perfed the primer and sent a bit of gas back my way.

For this reason I will never own a 243 since it is hard enough to keep the 7-08 out of the 308 brass....

January 13, 2007, 03:43 PM	#1
dirty habit Member Join Date: December 18, 2006 Location: New Zealand Posts: 57	7mm08 from 308 Hi, Just wondering if anybody out there knows how difficult or easy it is to form 7mm08 brass from 308? Is it a better idea to buy 7mm08 brass or reform? Cheers

January 13, 2007, 05:18 PM	#2
snuffy Senior Member Join Date: May 21, 2001 Location: Oshkosh wi. Posts: 3,055	It's as simple as lubing well, then running the .308 empty into your 7-08 full length sizing die. HOWEVER you will end up with a 7-08 casing that's shorter than a standard 7-08 by as much as .020. That's because the .308 is 2.015 and the 7-08 is 2.035 trim length. In the real world, that's not enough to be worried about, there's still plenty of neck to properly grip a bullet. Another thing that CAN happen when necking down, is the neck becomes thicker. If you are dealing with a tightly cut match chamber, it could result in no room left for expansion of the neck during firing, even preventing chambering in a worse case scenario. A standard sloppy factory chamber probably won't know the difference.

January 15, 2007, 04:57 PM	#3
Peter M. Eick Senior Member Join Date: August 4, 1999 Location: Houston, Texas Posts: 2,991	It is easy to do, but be careful to work up your loads carefully. The only blown rifle round I have fired was a 308 that ran though the 7-08 dies and was shot on a hot day. It perfed the primer and sent a bit of gas back my way. For this reason I will never own a 243 since it is hard enough to keep the 7-08 out of the 308 brass....