7 WSM from 300 WSM

Matt H

Matt H

New member
I have a tight necked 7 WSM. I am turning Norma 300 WSM brass to .012" prior to resizing it to 7mm. Since the 7 WSM is slightly longer to the neck, should I neck turn all the way to the shoulder of the 300 WSM, or stop short of that.

This is my first post: thanks for helping a newbie.

Matt
 
Always neckturn as far into the shoulder as possible.

Stopping short leaves the possibility of a donut of brass at the n/s junction.

al
 
alinwa said:
Always neckturn as far into the shoulder as possible.

Stopping short leaves the possibility of a donut of brass at the n/s junction.

al
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Since basically what he is doing is creating a fire forming shoulder when he necks down the .300 WSM to 7mm similar to the same thing that's done when making Dasher brass, if he neck turns to .012" while its still a .30 caliber cartridge where he quits neck turning at the original shoulder/neck junction will make a ridge on the inside of the shoulder when he moves the shoulder forward when he fireformed the necked down .300 WSM case to 7 WSM. At least, there shouldn't be a doughnut, but I doubt if the neck will still measure the .012" if its turned as a .300 and then necked down to 7 mm. The neck thickness woukd need to be checked after its necked down and posiibly returned as a 7mm if it needs to be .012" on the dot. The brass has to go somewhere and I'd guess that it would result in a thicker neck After its necked down.

If i was going to neck .300 WSM brass down to 7mm, I'd remove the expander from the 7 WSM full length die, neck it down to 7 WSM setting the fireforming shoulder for a good crush fit on his chamber. Then run them all through an expander die mandrel that matches the neck turner and neck turn to the fire forming shoulder. One thing about it, it would be easy to check and see if one way was any better than the other. It should show up on the target if it makes a difference. If it doesn't, then it doesn't matter.
 
Mike Bryant said:
Since basically what he is doing is creating a fire forming shoulder when he necks down the .300 WSM to 7mm similar to the same thing that's done when making Dasher brass, if he neck turns to .012" while its still a .30 caliber cartridge where he quits neck turning at the original shoulder/neck junction will make a ridge on the inside of the shoulder when he moves the shoulder forward when he fireformed the necked down .300 WSM case to 7 WSM. At least, there shouldn't be a doughnut, but I doubt if the neck will still measure the .012" if its turned as a .300 and then necked down to 7 mm. The neck thickness woukd need to be checked after its necked down and posiibly returned as a 7mm if it needs to be .012" on the dot. The brass has to go somewhere and I'd guess that it would result in a thicker neck After its necked down.

If i was going to neck .300 WSM brass down to 7mm, I'd remove the expander from the 7 WSM full length die, neck it down to 7 WSM setting the fireforming shoulder for a good crush fit on his chamber. Then run them all through an expander die mandrel that matches the neck turner and neck turn to the fire forming shoulder. One thing about it, it would be easy to check and see if one way was any better than the other. It should show up on the target if it makes a difference. If it doesn't, then it doesn't matter.
Click to expand...

Agreed :)

But then I'd neck down for wicked crush fireform fit, blow out with shotgun/pistol powder, NO BULLET, and then do all my neckturning.......

But then, I'd have fitted dies too....

And a fireform chamber....

etc

etc

al
 
greenguy said:
Why not use 270 wsm norma brass and neck up to 7 mm ?:)
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You could, but it wouldn't be any easier. The problem is that with the 7 WSM case they did the same thing with it as they did with the .280 Remington, they moved the shoulder forward about .038" from the parent case according to my chamber prints. The .280 Remington's shoulder is moved forward .052" from the parent .30-06 case. The .270 WSM, .300 WSM and the .325 WSM all use the same go gage. The 7 WSM uses a go gage that is approximately .038" longer. So, if you use .270 WSM brass to make 7 WSM brass, you'll need to neck it up to .30 caliber, then neck it back down to 7mm to created a fireforming shoulder about that same .038" in front of the original shoulder. If you're going to do that, then you may as well use the .300 WSM brass as it saves you a step. However, with all the shortages that are currently going on with brass and the other components, you just about have to use what brass you have to make whatever case you want. If you use .270 WSM brass and just neck it up to 7mm, then you'll create too much headspace again by that same .038" The cartridge companies don't do anything simple. I have a 7mm-.300 WSM reamer that I had made before the 7 WSM was brought to market. It has the same headspace as the .300 WSM. It would have been the logical 7mm, but they didn't do that for whatever reason. It sure wouldn't have been a safety concern as firing a 7-.300 WSM in a .300 WSM wouldn't have caused anything except a bullet wobbling down the barrel and poor accuracy and a lack of pressure build up.
 
Yep, but putting a 7WSM (if the same case as 300WSM) in a 270WSM would have caused some issues :cool: I think this was their fear when making the 7WSM.

The 7mm-270WSM is already a bit overbore for the 180's, I'd rechamber and save the hassles of forming brass just to be able to shoot Norma brass. The barrel won't last that long anyway, we're getting 900-1200rds before they start to go south. My experience is that Winny has more culls, but I don't see any difference in groups on paper between the two.
 
VT52 said:
Yep, but putting a 7WSM (if the same case as 300WSM) in a 270WSM would have caused some issues :cool: I think this was their fear when making the 7WSM.

The 7mm-270WSM is already a bit overbore for the 180's, I'd rechamber and save the hassles of forming brass just to be able to shoot Norma brass. The barrel won't last that long anyway, we're getting 900-1200rds before they start to go south. My experience is that Winny has more culls, but I don't see any difference in groups on paper between the two.
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It would have to be an awful sloppy chamber to be able to close the bolt on a 7mm-270 WSM in a .270 WSM chamber. However, you can't ever tell what people will do and what lengths they'll go to close the bolt on a cartridge. I would think that there would be more problem with someone trying to shoot a .270 WSM in a 7mm WSM chamber with the excess headspace that would result if did happen to fire.
 
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