7mmWSM vs 7/270WSM vs 7/300WSM

[Nomad47]

If you were going to build one of the three for 1000 yard competition (shooting the 180 Hybrids), which one would you choose.
I understand the 7mmWSM brass is only available from Winchester. I don't know about the other two. And I don't think the extra capacity of the 7mmWSM is needed.
Forming brass from the 270WSM would likely create a donut. Necking down from 300WSM would not create a donut but I think the necks would get thicker.

 

[RDavies]

When necking 300WSM brass down, yes the neck will get thicker, so you might have to neck turn. As it is a wildcat cartridge it is likely you will be neck turning anyway. You can get Winchester, Norma and Nosler brass in 300 WSM. The Norma and Nosler brass is the same brass, different name on the back.

 

[TonyR]

I've worked with all three and have found the 270WSM the easiest, but I neck turn everything and the donuts get cleared out as part of that process. One pass with the expander mandrel and you're at 7mm. I also seat the bullets pretty far out in the neck so they aren't near the donut anyway. The 270/300WSM cases have plenty of capacity for the Hybrids and I think the longer neck is a plus.

 

[Jeffvn]

I shoot the 7 WSM (for about 7 years now), but agree that the full capacity of the case is not needed to get a Berger 180 to the 2,900 fps node. (folks are doing just fine with the 7SAUM if they can find brass for it).

Winchester is not the only brass choice, as Norma and RWS (you can't get this brass in the USA anymore) make the brass; so does Hornady if my memory is working. I turn, prep, and sort the Winchester brass and have no difficulties. My Winchester brass is giving me between 12-15 firings (I anneal every second firing) before I recycle it.

As between the 270 and 300 WSM, the 300 necked to 7 seems to be the most frequent choice. (If my discussion with Lapua at SHOT was accurate, they will be producing 300WSM brass in the future) I considered changing to the 7/270WSM, (I think its the best alternative WSM case with about the optimum capacity to neck length), but still have a ton of the 7WSM brass from my original purchase lot awaiting use. So I'll be using the 7WSM for a long time.

Jeffvn

 

[Erik Cortina]

Bill, I would do the 7-270 WSM, it is the same as the 7-300 WSM but brass is cheaper.

 

[Nomad47]

Thanks, Guys. A friend of mine just bought a used Savage 270 WSM and plans to re-barrel to 7mmWSM. I suggested the 7/270 or 7/300 WSMs to him and wanted to make sure I was giving him accurate information.
Anybody know what loaded neck diameter is for unturned 270 or 300 converted brass?

 

[270wsm]

i guess i would ask, why not just use 270wsm with 175 Matrix they have a BC of .780 something

 

[Erik Cortina]

i guess i would ask, why not just use 270wsm with 175 Matrix they have a BC of .780 something

Because you would go broke after one match!

 

[338 Mollett]

300 round barrel !

 

[270wsm]

its not that bad. Matrix are 49.00 a 100d,Winchester brass is reasonable. i guess after looking through these threads, that is not verry expencive, compared to some of the stuff these other guys are using