7mm WSM from 300 WSM......or 270 WSM

Dmay

Dmay

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I've had about all the fighting I can take with the several batches of Winchester brass I've been using in my 7WSM.

Thinking to change to some Lapua or Norma and neck-down, or -up. Consensus seems to be necking down the 300 may be a slightly better way to go, just wondering if anybody here does this and any quirks you've run into.
 
You may want to check for availability and price as that may be the practical issue. I don't believe Lapua makes 270mm or 300 WSM brass. Norma apparently makes Nosler Brass, and weight sorts it. Hornady may be another choice.

As far as necking down or up, I have necked down lots of 7mm RM to .264 WM with no issues. You may want to measure some of your fired brass neck diameters and compare it to loaded rounds neck diameters of your loaded brass. That will give you some idea how large the neck is in your chamber. If it is large, you may benefit more from necking down in size which will thicken the neck brass. If your neck is smaller, necking up may be better, as it will thin the brass somewhat. I like Lapua brass if I can get it. It is not as expensive as the Norma/Nosler and I believe just as good or better. Don't know much about the Hornady or if it is a choice.

On a quick look I think your only choice is Norma/Nosler 270 WSM. I don't see the 300WSM in their list, and Hornady don't appear to make either. It should neck up fine.
 
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Necking down from 300 WSM is easiest, "or you can use 270 WSM brass, expand the neck to 30 cal, then size in a 7mm WSM die to form a secondary shoulder that will properly head space" - as per Shooting Times Magazine, Nov 2016 issue pg. 40

Cheers
 
Actually if you look carefully at the dimensions, you'll notice that the 7mmWSM is different than the 300 or 270 WSM. If you can get them to fit, the 270 WSM out to 284 is the preferred method. The WSMs have very thick necks and going out 7 thou is nothing, but bringing the 300 WSM down to 7mm may cause your necks to need turning. This requires special tools (if you don't already have them) and is a real PITA.
My recommendation is blow the 270 out. My 300 WSM has serious neck splitting issues and I wouldn't recommend anyone work the necks any more than absolutely necessary. It seems to be a case problem and I am not the only one with these problems, it's all over.
 
c-fbmi said:
My 300 WSM has serious neck splitting issues and I wouldn't recommend anyone work the necks any more than absolutely necessary. It seems to be a case problem and I am not the only one with these problems, it's all over.
Click to expand...

You may want to consider getting a Lee Collet Neck die. I think they are only about $26 or so. A collet die works the neck brass a lot less than standard sizing down and then back up with an expander ball. The even better option is to use a Forster Bushing Bump Die. Will cost you a bit more, but the advantage over the Lee is that you have control of the sizes by interchanging bushings, and you can bump the shoulder back 0.001" to ensure it fits your chamber. And there is also the annealing which should be done ever 3-5 reloads...
 
Dmay said:
I've had about all the fighting I can take with the several batches of Winchester brass I've been using in my 7WSM.

Thinking to change to some Lapua or Norma and neck-down, or -up. Consensus seems to be necking down the 300 may be a slightly better way to go, just wondering if anybody here does this and any quirks you've run into.
Click to expand...
What issues are you having exactly?
Is the brass nickel plated?
If the issue is sizing have you tried annealing?
 
thump_rrr said:
What issues are you having exactly?
Is the brass nickel plated?
If the issue is sizing have you tried annealing?
Click to expand...

Main issue is the fact that I have four batches of brass and they all act different. One batch shows pressure with a load that shoots well in another batch. None of it is nickel plated, and I think I let the necks get thick on one bunch, but I'd just like to start over, hopefully with some better consistency among the brass......

Not sure yet which way I'll go, have all winter to work on it I guess.... Turning necks is no problem, do it all the time, and I use bushing dies anyway, so sizing and annealing when needed isn't a big deal.....

Anyway, thank you to all for the responses. I appreciate it.
 
Check the headspace dimension of the 7 vs the other 2. if memory serves, the shoulder is forward in the 7.

300WSM is easier to find and you can form the false shoulder in 1 step. COW form and away you go.

There is now Betram 7WSM if you want to skip all this BUT not sure how good it is vs the norma/forming route.

Either way, there are options... just not very cheap ones

Jerry
 
Dmay said:
I've had about all the fighting I can take with the several batches of Winchester brass I've been using in my 7WSM.

Thinking to change to some Lapua or Norma and neck-down, or -up. Consensus seems to be necking down the 300 may be a slightly better way to go, just wondering if anybody here does this and any quirks you've run into.
Click to expand...

Hornady was listening. Hopefully available early 2018.
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View attachment 125199I've done a bunch of 7wsm from 300, it's a royal pain for sure. I start by necking down leaving a shoulder in the neck. Then 16gr of unique with a full case of cream of wheat and a tissue paper plug. Then I outside neck turn to .012" and the final step is annealing.

The next time I make 7wsm I'll be trying 270wsm brass and necking up to .284 with a redding bushing die, I bought a bushing to set some extra neck tension, hoping to form by jamming the bullet hard with full power loads.
 
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Consider that when you neck up, you will put shoulder material into the base of the new case neck... instant donuts.

2nd, you have to move the shoulder forward and using a jammed bullet and high pressure loads can really strain the web area of a case. Once damaged, case durability is greatly reduced.

300WSM necked down and formed as you have described is the best way to form the 7WSM.

Plan B would be to just buy 7WSM when they become available.

Jerry
 
I would think Hornady brass would be the answer.
Winchester hasn’t marketed 7mm WSM brass for years.

Always great to see new choices. Especially if a person has limited time for the extra steps needed for necking down, bumping, etc...
 
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