.308 to 7mm-08

Hi all!
I have been looking high and low and left and right for once fired 7mm-08 brass and just cannot for the life of me find any decent amounts or quality. I have found plenty of .308 brass and am starting to consider how tough it would be to convert .308 brass to 7mm-08. Has anyone done this or tried this? Is it safe to do so as well? would I have to rework up loads?
Thanks guys!

I’ve never done this, but everything I’ve researched says that the 7mm-08 is just a necked down .308. I would imagine there’s quite a process to get the brass necked down. Really, a 7mm-08 is between a .308 and a .243, and I believe all 3 could use the same brass. I’m sure some experienced folks will chime in…

check with dillon 1-800-223-4570,if they dont have it,they can put you in contact with someone that does.

There is no forming die for .308 to 7-08. They are directly formed.

In theory, you can run a well-lubed .308 case directly through a 7-08 full length resizing die (in several stages) and you end up with…wait for it…7-08 brass. Notice the WELL LUBED part. Have a stuck case extractor at the ready! If you don’t own one, get one, they are well worth having as sooner or later you will need one.

It’s a little more complicated than that, but basically you form 308 with a 7-08 die. Longer rundown at the end of this post.

However. There’s always a however.

In practice, what I’ve frequently heard happens is that necking down the 308 thickens the neck a few thousandths, so then the brass won’t chamber once loaded. The only solution is neck turning to reduce the thickness at the neck, which is possible, but a PITA and of course getting tooled up adds cost.

Now again, in practice, how much of a problem you have with neck thickness depends on the dimensions of the brass you start with. Many guys report problems with Brand X, but no problems with Brand Y. The dimensions of the neck were just thin enough to allow for chambering.

So here’s what I’d do. Try forming couple and see what happens

Can anyone on the forum send Carter aa few empty 308 cases? Maybe 3 of one brand and 3 of another?

Obviously, caution must be used with reformed .308 cases for the again obvious reason. Personally, I would mark the ends red with marker.

Grouse

Full rundown that I found on a reloading site:

1.
I use an RCBS full length resizing die for 7mm-08.
Neck reducing loads are high and good lubrication is essential. Failure will result in a stuck case. I prefer RCBS-2 over Imperial. But, the RCBS-2 has to be replenished more often. Remove the expander stem. Step down the die about 2 turns at a time per stroke after the neck begins reducing.

2. About half way through the neck forming, stop and wipe of all the lube with paper towel. Trim the half finished case to a preset 2.025. [Not only is the neck getting thicker, but it is getting longer. This is just a precaution to assure the neck mouth does not run out of clearance in the die. YMMV] Then relube afresh, both neck and body. Debur the mouth and resume forming.

3. Use a RCBS precision mike to begin measuring shoulder set back when the shell holder nears the die bottom. I shoot for zero to -.003 (SAAMI 1.630 shoulder to rim) and stop there. Any precision mike for the .308 case form (.243, 7mm, .308, etc.) will work for this measurement.

4. Now install and set the expander stem and the die height so that the expander opens the neck, the decapping pin just pushes out the old primer (if these are 1X cases), and the neck does not reenter the neck reducing section of the die. Make sure the expander ball is cleaned and well lubricated with RCBS-2 before installing. This takes a little experimenting to get set correctly, and requires some tactile feed back on the ram handle to feel with the expander is working or running clear.

5. Remove the case, and trim again.

6. Now there is an internal ring of brass material built up inside the case at the junction of the neck and shoulder. Also the neck is extra thick, but has been formed out to “almost” the correct ID by the expander ball. Most of the thicker neck material is now on the outside. In order to control neck-to-bullet tension and assure proper clearance of the neck and chamber, the neck must be turned. RCBS has a neck turning attachment 98861 for the various calibers. It consists of a neck inside diameter reamer and a neck peeling cutter that work simultaneously and retrofit into their RCBS trimpro. I plunge and reverse the reamer and peeler two or three times to clear the turnings. Also clean and relube the shank of the reamer to reduce turning friction and torque.

The key is keeping the expander stem out of action during the neck forming. The neck gets thicker and the die and expander will not work simultaneously with that extra brass thickness.

I see plenty on the gunbroker.com, but most is priced at more than $1.00/piece. I did not realize this was a caliber that gets a premium price for used brass. Before I’d pay that amount I would buy factory ammo and save that brass when fired.

Thanks for the replies guys! i got lucky and just found a range close by that has a ton of 7mm-08 brass for decent prices. I did pick up some .308 however just to tinker with it a little bit and see what I can come up with.

Youbetcha wrote:

Thanks for the replies guys! i got lucky and just found a range close by that has a ton of 7mm-08 brass for decent prices. I did pick up some .308 however just to tinker with it a little bit and see what I can come up with.

Good deal Carter.

I would certainly think it would be worth your time to do a little science experiment and see if you can form .308 into 7-08 directly. If you can identify a brass brand or brands that form and most importantly chamber properly in your rifle, you should have no trouble going to one of the bulk brass sites on the internet and buying a large quantity of that pure headstamp and you should be all set.

And for very low cost! .308 brass is soooooo cheap and available because of all the military and LE users out there.

Grouse