.308 win to 7mm 08


uk roe hunter
August 3, 2007, 02:53 PM
I am about to get a 7mm08 and i wondered if it is possible to just full length resize some .308win brass to use in it?


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August 3, 2007, 03:05 PM

But the brass has to go somewhere. In the case of this operation, the thickness of the walls of the case necks will be increased. You may need to take this into account in your load development, and component maintenance. Turning case necks is rather a nuisance.

August 3, 2007, 03:12 PM
Want to look into expanding 243 brass. I think that you can, but I am not 100% on that.

August 4, 2007, 04:54 PM
I've made 7mm-08 brass from both .308 as well as .243.

The .243 worked better as the necks were more uniform, but were probably that way before I expanded/reformed them.

With the .308 brass, you can practically rest assured that they'll be too long and will need trimming and chamfering.

If you have the means, Neck turning will also be of a substantial be of a benefit.

The difficulty of reforming won't be in the neck, but will be dependant on the shoulder and head area. And this will depend on the chamber dimensions of the rifle it was fired in previously.

I tried reforming some that had been fired in a fluted chamber. Cases split and were unusable.

August 4, 2007, 04:58 PM
related question: can I resize .308 to 243? and if yes, what die do I need?

August 4, 2007, 05:13 PM
You may run into problems with sizing them down that much. It can be done, and I've done it.

I first ran the .308 into a .308 die, then down to 7mm, before sizing them down to .243. You may have problems with collapsed necks and dented necks from the sizing lube.

However, it is much preferable to just order/purchase some .243 brass. Ditto, 7mm/08 brass........... About $26-32/100 from MidwayUSA.

Peter M. Eick
August 4, 2007, 08:17 PM
As a side comment, the only blown primer I have ever had was from a 243 that accidentally got sized up to 7-08 and mixed into my 7-08 brass. Take a hot load and a very hot day and the bit of difference in the internal capacity resulted in a big puff of gas in my face an a blown primer in my 700 BDL.

Ever since then I am paranoid about keeping the 308's from the 7-08's and I swore I would never own a 243 (I went the 25-06 route instead).

August 4, 2007, 10:11 PM
Sure, but why bother. 7mm-08 ammo and brass isn't exactly rare.
"...can I resize .308 to 243?..." Same response. .243 ammo and brass is even more common than 7mm-08. You'd have to ream the inside of the case mouths at least.
For either of these, it's more trouble than it's worth.

August 5, 2007, 01:09 PM
One thing I haven't seen mentioned is the difference in nominal case lengths,
.308 win, 2.015,-- 7-08, 2.035.
This means that when necking a .308 down, you end up with a 7-08 case that's .020 short. No big deal, just be aware that neck tension will be less,, because of a shorter neck, but may be compensated for by the neck being thicker. Also trimming to square up the mouth, could only be done with a trimmer adjustable to less than minimum trim-to-length,(that leaves out the lee system).

A better bet is necking UP from .243,( .243, 2.045), would result in a case that's .010 LONGER than a 7-08 should be. Also the necks would be a mite thinner than normal 7-08 brass.

As has been said, 7-08 brass is inexpensive, plentiful, and the headstamp is correct!

uk roe hunter
August 5, 2007, 02:10 PM
thanks guys,
I have hundreds of cases of decent .243 brass so I will size that up to 7mm 08.


uk roe hunter
August 23, 2007, 12:23 PM
I sized up some .243 win and it was fine. but it is only the first load with it, I wonder how many loads it will have in it? only time will tell,


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