necking down 300 win to 7mm mag

blackie9999

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hello.i can get a hold of 350 rounds 300 win mag brass new in bag.i was wondering if it can be necked down to be used in my 7 mm rem mag has i am getting into reloading.what has to be done if it can be done.thanks
 
Wrong size case. If you had some .338 then you could neck it down to 7mm.

300WM.png

7remingtonmagnum.jpg
 
Also, the 7mm is a belted case and headspaces on the belt. No belt on the .300 since it headspaces on the shoulder. Maybe you could solder a belt on it?
 
No belt on the .300 since it headspaces on the shoulder.

Totally incorrect,the 300winmag most definitely has a belt.

I was actually tempted to cut and paste the rude response that you gave to another poster in the varmint grenade thread,but I just couldn't justify stooping to such a low level.:rolleyes:
 
Yes, it can be done, but it's a pain in the ass and not worth the time and effort. You have to push the shoulder back and shorten the case, as well as neck it down. And as Stubble says, they are both indeed belted cases. Don't bother. If you get the 300 Win Mag cases at a good enough deal, sell them and buy 7 Rem Mag brass. Way better way to go. - dan
 
Ignore Rookie Wildcat as he shows the "rookie" part.

Listen to dan. It is more work than the cases are worth, even though it can be done. Someone must want the .300 cases. Spend whatever you get for them on the correct cases and save a lot of effort.
 
I would only consider doing this if I was going to rechamber the rifle to a bore eating 7mm/.300 Winchester wildcat, thus making it impossible to shoot 7mm Remington ammo. I believe that ballistically speaking this would meet and possibly exceeds the point of diminishing returns, although you might gain some neck length over the .300 Winchester's very short neck which wouldn't hurt any. After all, there has been more than one person who bought an even larger 7 STW only to find that it produced the same velocity as the 7 mag. The 7 mag is so good as it stands there seems to be little advantage to messing with it regardless of how much .300 Winchester brass you have. Better to just pick up a .300 Winchester rifle or as Dan said, swap the brass for 7mm Remington brass.
 
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