How to neck .308 brass down to 7mm-08?

gfol70

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I'm interested in getting a Sako A7 in 7mm-08 but am concerned about ammo cost and avail. I reload.

I would like to know how to neck 308 brass down to 7mm-08. What is the process? What dies do I need? Issues of concern?

I looked on the web but found little info.

Thanks

Guy
 
I do this process with Lapua brass.

I full length resize with proper lube.Then clean the cases.I then run them through a neck collet sizer just to ensure they will chamber, not necessary but just a step I do.

I ensure they all chamber, then fireform with 4.5 - 5 grains of pistol powder and the cream of wheat method.

After that I anneal the necks and carry on per normal, usually only neck sizing.
 
Its as simple as running your .308 cases into a 7mm-08 die, your main concern with how much thicker the necks will be. Depending on your brass and chamber you may have to turn the necks, read post #6 and #13 in the link below. Bottom line, just order and stock up on 7mm-08 brass or get good at neck turning.

.308 case to 7mm 08 case?
http://forum.accurateshooter.com/index.php?topic=3753141.0

NOTE: If your chamber has a tight neck and the neck down cases have a thick neck there will not be enough room for the neck to expand, this can cause a pressure spike or even a kaboom. If you don't have neck turning tools and a gauge for measuring neck thickness just buy 7mm-08 cases.

Tools for Measuring Case Necks
http://www.6mmbr.com/casenecktools.html

Preparing Cases for Long-Range Accuracy
http://www.accurateshooter.com/featured/complete-precision-case-prep/
 
I've done it for years and never had to do anything other than full length size and prime charge with powder and seat the bullet and go hunting.

I think that's the way we all did things, prior to the internet and the era of super caution.
I did a lot of 30-06 to 270 that way, without any sign of a problem.
 
Sizing a .308 to 7mm will thicken the neck walls slightly. Whether this results in a problem will depend on the chamber. Easy enough to seat a bullet in a case and check to see if the neck over the seated bullet is tight in the chamber.
 
If always had much better results necking .243 bras up to 7-08. The necks weren't to thick band I had great cash life.
I did add an extra step to make it a bit easier though. I put a sizing ball from a .257 Roberts die in the 7-08 die to get it stared, then the 7mm bal bto finish. It was easier on the brass and a lot easier on my arm! Cases tended to be a tiny bit short until they were fired.
 
Thanks for the pointers all. I like to get 7mm-08 but there just isn't any brass up here - hard enough to find 308. I guess I just don't want to go and buy a rifle in that caliber and end up having to pay through the nose for ammo - if I can actually find it.

What I find appealing about what I've read re 7mm-08 is the lower recoil yet still good ballistics and take down power.
 
Mail order the brass. It is easy to find if you look at the sponsors here, or even the big stores (Cabelas, Bass Pro, Wholesale).
I agree on the cartridge - very good round!
 
Wish that was the case chrismc - not a single source of brass in 708mm let alone most other calibers. If you know of a source - please let me know. Thanks.
 
I've ran my 308 brass through a full length sizer and have had no problems, I would however be careful using Federal brass as the necks are thicker than the Win brass I use. I always measure mine for neck dia just in case.

G
 
I make all of my 7mm-08 brass from .308 cases. My process is as simple as running it into the full length sizing die, chamfering the case mouth, loading with my hunting loads and shooting them. I will trim the lot to a common length after the first firing. No problems using Federal cases either; the most common brass I use.
 
If always had much better results necking .243 bras up to 7-08. The necks weren't to thick band I had great cash life.
I did add an extra step to make it a bit easier though. I put a sizing ball from a .257 Roberts die in the 7-08 die to get it stared, then the 7mm bal bto finish. It was easier on the brass and a lot easier on my arm! Cases tended to be a tiny bit short until they were fired.

This would be my route. Especially right now when .308 brass seems to be in short supply.
 
There really isn't a good reason to size down 308 brass if the properly marked 7-08 brass is available.

Mind you, with the price of a bag of brass cases these days, maybe there is a good reason, especially if you can get some once fired cases or even range brass to neck down.

I've modified cases to fit on several different cartridges when the proper ones just aren't available or often, a couple of bucks apiece.

I have swaged down the 308 case to 257 and expanded the necks to 338 and 358.

When I reduced the case neck to 257, I annealed the the neck and shoulders on once fired brass to dead soft. To soft for good bullet retention IMHO. The 25-08 is a fantastic performer by the way. Even though the case capacity is within a few grains of the 257 Roberts, in modern rifles it can be loaded to some very quick velocities, even rivaling the 25-06 with all but the heaviest bullets.

The 7-08 is a shooters dream. Because of the modern rifles chambered for it, and because of case shape it is the kissing cousin of the tried and true 7x57 but able to load even heavy bullets into the case without taking up powder space, even in a short action. The loads given in most manuals push similar weight bullets faster than the 7x57 loads which of course are held to lower pressures because of the older and supposedly weaker actions it was designed for.

Time to get back on topic. I went to the loading bench with a couple of once fired 308 Win cases from the appropriate bin. The cases, were Winchester, not my favorite but if these worked, anything will work.

I cleaned up the brass and lubed the inside of the neck as well as the outside of the case. Then, I screwed in the full length sizing die for the 7-08, put in a #2 shell head holder and inserted the first case. It went without a hitch. Of course, there was a bit more resistance than usual but not enough for the RCBS JR press to notice. There would be even less in a Rock Chucker or something similar.

I never noticed any thickening of the case neck but I did notice that it was to long and the case mouth wasn't even. It was uniform in thickness all the way around though. Yes, differing thicknesses around the neck can cause some minor accuracy issues. Only if you're really anal though or a bench rest competitor, which is basically the same thing. The extra brass has to go somewhere, if not into the sidewall of the neck, then it has to go onto the end around the case mouth.

The second, third, fourth and fifth cases all swaged down smoothly as well, with only one pass needed to get it all the way down to the base of the neck/shoulder. All needed to be trimmed for length before loading.

The reason I was curious as to how easy this would be is because with the 25-08, if I didn't anneal the necks dead soft, the shoulders would collapse on many of the cases. The next batch of cases were made by necking up 243 cases and fire forming with the first load. There was no indication of this happening at all on necking down to 7mm. You might want to set the shoulder back a bit as well. Some chambers are a few thousandths of an inch shorter and your case body/shoulder may be a bit long. I loaded these cases with 160 grain bullets over W760 and CCI 250 primers. At least they will be useful. In my box, these have RED colored bases, done with a RED Sharpie. I have put a note on the underside of the lid to explain what and why the RED bases are about.

You may want to do something similar. I really have an aversion against cases with misrepresenting cartridge designations on the face. In this particular instance, not really a safety issue as if you were to load and fire them in a rifle chambered for 308Win, there would be little if any recoil and the case would fire form back to its original form.
 
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I noticed that SFRC has quite a bit of brass in store although not listed on their website: They are a site sponsor so contact information can be found on the link.

If they are out, I've got about 200-240 once fired Federal Gold Medal 308 brass and about 60 Hornady Match once fired as well (and two or three boxes live of the latter): Left over from a match I shot with someone else's rifle. I have had it in storage for a couple years now and only keep it for two reasons: First, I've thought of getting a 260rem rifle, and last but not least, I don't throw out things that aren't junk. I doubt I'll ever use it, so if you are hard up for brass to resize I could be enticed to sell for a mutually acceptable price. I live a short distance north of Kingston, in SFRCs neck of the woods if you are ever frequent the area. Any interests, I'll do a physical count. Also about 50 range pickups of assorted stamps in 308 as well a few 7mm-08.
 
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