I'd like to shoot my 7-08 a bit more at the range but am short on cases.

I have a heap of RWS 308 cases. How unwise is it to form 7-08 from 308?

I tried one and it seemed a cinch. Not sure what the neck dimensions of loaded rounds should be for a factory M700 7-08 (to avoid pinch from overly thick necks)

My concern is aged eyesight and the potential for chambering in my 308.

i have done that before, shot good, some might need trimming, but just go to MIDWAY-USA and get 50 pcs for $24.00 STARLINE brass I bought 100 pcs, 2 years it loads / shoots very good.. Natchez shooting supply has Hornady 7-08 brass 50 pc. for $19.00

When my son brought a 7mm-08 for the DIL brass was hard to find.

I have a lot of 308 and 243. I tried both I found Federal 243 cases made best and easiest 7mm-08 cases.

Then I found some 7-mm08 brass and haven't formed any more.

make 7-08 out of 308 works just fine.

We make a lot of cases from the 308.

7mm-08, 260 Remington, 243 Winchester, 22-243 Middlestead t .

Some require neck turning, depending on chamber.

quote:

Originally posted by 1894mk2: Not sure what the neck dimensions of loaded rounds should be for a factory M700 7-08 (to avoid pinch from overly thick necks)

Measure a fired case from your particular rifle and compare it to your loaded rounds made with 308 brass. The loaded round should chamber easily and be smaller than the fired case by a few thou.

Most factory chambers are pretty generous, but it's pretty easy to measure things and reassure yourself.

I did it for a 7-08 a long time ago; it worked without reaming. It is very easy; but yes, check your loads to make sure they chamber freely. If they drop in and extract freely before firing, then they are ok. If they don't, then the necks are too thick. You don't have to actually measure anything. If you do, you need a chamber cast first.
Use the chamber as a gauge.

Running .308's into a 7-08 FL sizing die is silly simple, requires no intermediate step, and makes usable cases with a single stroke. It would be a very unusual factory chamber that required neck thinning (my .243's don't even require neck thinning when made from .308 brass).

Be sure to lubricate adequately, but don't over-lubricate, which will cause shoulder dents. (Shoulder dents don't make the case unusable or dangerous, they just don't look good but will iron out upon firing.)

As far as confusing the reformed 7-08 round with a .308 and inadvertently shooting it in a .308 rifle, no harm will be done (particularly to the roe deer). The greatly undersized bullet will just careen down the oversized bore with very low pressure behind it and fly with approximately the accuracy of a ball from a smooth bore musket. Other than expanding your case mouth back to .30 caliber (and likely blackening half of the case with soot), nothing bad or even remotely dangerous will happen.

quote:

Originally posted by 1894mk2:
I'd like to shoot my 7-08 a bit more at the range but am short on cases.

I have a heap of RWS 308 cases. How unwise is it to form 7-08 from 308?

I tried one and it seemed a cinch. Not sure what the neck dimensions of loaded rounds should be for a factory M700 7-08 (to avoid pinch from overly thick necks)

My concern is aged eyesight and the potential for chambering in my 308.

To avoid any possible mix-up of .25-06 and 6.5-06 ammo I'm loading my 6.5-06 hunting ammo with nickel plated cases and .25-06 ammo using brass cases.I assume that you're using distinctly different bullet types for the 7mm and .308

That is actually a problem? You just keep them in separate boxes. This system has worked for me for many decades now.
I have never confused one cartridge for another.
Here is how you do it; Put all your 7mms in a green plastic box and all your 308s in a red plastic box. And mark them in big letters with a Magic Marker.

quote:

And mark them in big letters with a Magic Marker.

Yes, use Magic Marker. Sharpies are now reserved for revising weather forecasts.

RWS cases are one of the best so if spare I would size them to 7mm-08 and expect to get long life from them.
I have sized 308 to 7mm-08 without neck turning, most common rifles will have chambers that are slightly generous around the neck area so highly unlikely you would experience any problems, just as most other posters have said.

Easy check for neck tension (neck thickness) is to load a couple with minimum load data and fire them.

Then test to see if a bullet will slide through the case necks on the fired brass. If they do, You're good-to-go without neck turning.

Zeke

PS: I'll scuff-neck-turn brass even when a thinner neck isn't called for because it trues it up a bit and aids in concentricity...but then I'm anal and like to reload and tinker.

I've been case forming from 243 + 308 for years with good results. I will say though that like with any case forming operation on a different headstamp I am careful who I let have them. Down the road, you never know who might end up with them.

I do a lot of this sort of thing, I would rather neck a case up than down, sometimes necking down thickens the neck and requires inside neck reaming to cut the donut out where the neck meets the shoulder..but neck reaming is just an additional step in the process..

All went well. Thanks for the help.