7mm-308 vs. 7mm-08

[Statzer]

Good morning ladies and gentlemen,

A moment of your time if you will..............

I realize and understand the history/difference between the 7mm-308 and 7mm-08, but, am in need of quality brass for a 7mm-08 and Lapua appears to fill that requirement, but, only in 308, not 7mm-08.

My question is...........can I reliably and safely form 308 brass to 7mm-308 and fire it in a 7mm-08 chamber?  Will the shorter cgt. cause problems?

Respectfully submitted,

Roger

[helotaxi]

It's likely that the cartridge case will lengthen as you neck it down.  People have successfully formed the even longer .243 Win from mil 7.62x51 (.308) brass.

But another possibility is neck up .243 Win or .260 Rem brass.  The .260 is the same length as the 7-08 and the .243 is longer.

[wncchester]

That's fine.  In fact, it's the way it was originally done back when it was a wildcat.

[Steve P]

My question is...........can I reliably and safely form 308 brass to 7mm-308 and fire it in a 7mm-08 chamber?  Yes, you can.
Will the shorter cgt. cause problems?  No
/quote]


Steve

[bilmac]

About half of my 270 cases are made from 30-06 cases. I almost prefer them because it's a long time before you have to worry about trimming them.

[necchi]

I'm not understanding something,,
I have a 308, and I have a 7mm-08,,is there some round out there called a 7mm-308 that is some how different?

Other wise, Yes you can make 7-08 out of 308

[Statzer]

Yes,  back "in the days", when the 7mm-308 was still a wildcat it was basically a 308 necked down to 7mm-308.  Remington then brought the ctg. out into what we now have as the 7mm08 which has a slightly longer neck than the original wildcat.  The performance is virtually the same.

With regard,

Roger

[shot1]

Get the 243 cases and neck them up and you will have the same length as a regular 7mm-08.  Use a tapered expander ball in your die. Lee dies already have a tapered and I think Hornady also does. Nothing wrong with necking down the 306 though.

[necchi]

TY, for the history lesson Statzer.

 Haveing both rounds I'm know about the length differance, and it's one of the reasons I chose to purchase 708 cases.

 My 708 rifle has a really loong chamber throat! As an example a Sierra 150 Game King will leave the case before I reach the lands, I know it's only a .020 diff, but i want every bit i can get. I take that back,,that's the 308,,but the 708 does have a chamber neck that's at 2.071.
 
 Now Lapau is some really good brass,,really good price too,,

So if chamber length is an issue for ya,, necking up the .243 might be a better option for ya. They are the same case according to dimentional masurements.
Steves pages are handi to look at,,
http://stevespages.com/page8d.htm

[helotaxi]

From the datum line to the case head, the .308, .358 Win, .338 Fed, .243 Win, .260 Rem and 7mm-08 are all exactly the same, which makes sense since all of the others are simply the .308 necked up or down.  The .243 gains the most length (2.045") over the .308 because of the distance from the shoulder to the neck.  The .260 and 7mm-08 are the same length (2.035"), which is slightly more than the .308 (2.015").

Any difference in length caused by forming your 7-08 from .308 will be in the neck.  The rounds will chamber just fine, but neck tension will be slightly less unless you use a slightly smaller neck bushing and expander to make up for the lack of bearing length.  If that concerns you, .243 brass is readily available.

[yooper77]

Any cartridge that can be formed from a parent cartridge without moving the shoulder angle is a semi-wildcat not a true wildcat.  7mm-308 = 7mm-08
I also hand load another semi-wildcat, 338-06 A-Square I use 30-06 Springfield brass.

I use and prefer 308 Winchester brass for my 7mm-08 Remington hand loads.  I have a lot of 308 Win brass so I save lots of money and suffer zero drawbacks.

yooper77