I am contemplating trading my 280 M700 Mountain Rifle in on a Kimber M8400 in 7mm WSM.

I can't find a source for brass other than Winchester. Does Norma make 7mm WSM brass? Thier website doesn't seem to be working as I can only accesss the home page.

I have found several sources for Norma 270 WSM and 300 WSM, but no 7mm WSM.

I just visited the Norma website. They don't make brass for the 7mm WSM.

I don't believe Norma makes 7mm WSM brass. As others have stated the shoulder on the 7mm is moved slightly forward to keep someone from trying to shoot it in a 270 WSM. If you must have Norma brass buy 300 WSM brass and then run it in your 7mm WSM die. It should form a shoulder on the neck. Since the 7mm and 300 have the same length you should check to insure that necking down didn't increase the length to far. If this new shoulder isn't large enough to stop the case then enlarge the neck first and then run it in your die. Then anneal.

Folks-

Doesn't the 7mm WSM have a different shoulder position and thus headspaces differently than the .300 and .270 WSM?

It seems like I have read that somewhere thus, if you were to neck down .30 WSM brass to 7mm you might have a rather significant headspace problem; to the point of case rupture.

I wasn't aware of the headspace problem. Why do they do that?

So one cannot put a 7MM WSM into a 270 WSM chamber and fire it. This was necessary with the 270 Win and 280 Rem, also.

I've been using Winchester brass in my Dad's .270 WSM with excellent results. I wouldn't feel bad about buying a 7 if the only brass is Win.

I had some trouble sourcing 7mm brass for my rifle and went the necking down .300wsm cases route. I short sized the necks and used the bump on the neck to off set the headspace problem. I had no problem with headspace and all the cases fire formed with moderate loads. just be sure not to use too low a load for fire forming and it is fine.

all the best

Murph

I hope to be in the same boat as you shortly, in that I want a 7mm WSM.

What I am Going to do is get some 270WSM norma cases and load them with about 15 grains of a very fast burning powder(probably shotgun) use a filler(baby cerial) to fill the rest of the case then seal the necks with wax and fire them in my 7mm WSM.

I buy lapua 243 cases and use this method to fireform them into 7mm-08 cases, it works very well indeed.

I know its going to a bit of trouble but my lapua fire formed cases are outlasting remington 7mm-08 cases by a long shot.

Well worth the effort as far as i'm concerned.

UPDATE

A few weeks after my initial post, I traded the 280 M700 Mountain Rifle in on a 280 M700 CDL.

The chamber of the Mountain Rifle was about .005" off center with the expected poor accuracy. Remington told me "that shouldn't affect accuracy".

The best it would do was 2 1/2"-3" groups @ 100 yards, not good enough as 90% of my deer are killed @ between 230 and 250 yards. I have a sweet bottle neck set up and the long distance keeps my scent away from the "hot spot" allowing me to hunt the same tri-pod stand for weeks on end.

I had made several "marginal hits" with the Mountain Rifle and it was just a matter of time untill I lost an animal.

The 280 M700 CDL will shoot just over 1 MOA with the Hornady 139 grain Interbonds that I prefer.

2 1/2" of error factor at that distance is a lot better than 6 1/4" - 7 1/2"".