7-300WSM Dies

[Kyle Schultz]

Thinking of building 7-300WSM. Will neck down Norma 300WSM brass.

What's the most straightforward way of getting fixed up on dies?

I can use a standard 7WSM seating die right? But what about the sizing die? I have Warner sizing die that I can swap out the insert. But those are cut off fired brass. Will a Redding 7WSM Type S bushing neck sizing die work to size the necks initially? My concern is that bushing dies won't size the full length of the neck. That's a problem since I plan to turn the necks down to give a loaded neck diameter of 0.310".

Any suggestions?

 

[twoodard]

the 7wsm has a longer case than the 300 from rim to shoulder. i would think a 300 die with correct bushing would do it for you

 

[Erik Cortina]

Kyle, get a 270 WSM type S bushing die, and use whatever bushing suits your needs.

The 270 WSM and the 300 WSM are the same except for the neck diameter, the 7mm WSM has the shoulder pushed forward about .030". So, either neck up 270 WSM or neck down 300 WSM, either way works.

As for seating die, I would think you could use a 270 WSM Wilson and just buy the 7mm seating stem for it.

 

[Yellow11]

You might consider also buying a 7/300 FL resizing die for your initial sizing, as the neck bushing route will exclude the base of the neck.

I start with a neck bushing die with a bush size half way between where I start and where I want to finish, then swop to the FL die, expander mandrel and then final sizing neck bush.

 

[Erik Cortina]

That's why I prefer to neck up 270 WSM. Run expanding mandrel, turn necks, seat bullet and shoot. Simple!

 

[Kyle Schultz]

Thanks for the comments.

Deliberately chose necking 300WSM down rather than necking 270WSM up. Had too many split necks when I necked 6.5x284 up to 7mm. Plus I was influenced by the advice give on the 7mm cartridge guide.

 

[Erik Cortina]

Thanks for the comments.

Deliberately chose necking 300WSM down rather than necking 270WSM up. Had too many split necks when I necked 6.5x284 up to 7mm. Plus I was influenced by the advice give on the 7mm cartridge guide.

I have never split a neck necking up from .264" to .284", but maybe I'm lucky.

Also, when you neck up 270 WSM, you are only necking up .007" as opposed to .020" as you did with the 6.5mm, so you are 65% of the way there with the 270.

Last but not least, I find 270 WSM easier to find.

Either way good luck and let us know how it turns out!

 

[Steve Blair]

I've expanded ~800 Lapua 6.5-284 cases to .284 and only had a problem with two "wrinkle-neck" cases. Previously fired brass was annealed first, then expanded. New cases didn't need it. The Sinclair expander and Ballistol inside the neck worked well. If you use Ballistol, make sure you have good ventilation or a gas mask. [br]
Erik's point is well taken. Some factory brass requires almost a .007" expansion when new, just to load it.

 

[Yagingaboy]

I bought a FL die set from Redding in 7X300 WSM. They had them right on the shelf. Only took a few days to get it. The set was around $115 if I remember.

 

[maxpower]

I,m using a 300WSM Redding S type die with bushings to suit 7mm. Does anyone know what size neck the 270 WSM non bushing dies have? Wondering if they will fit neck turned 7mm/300WSM?

 

[Kyle Schultz]

Update:

Spoke to Forster. They believe they can hone out the neck of a 270WSM FL sizing die for minimal cost. Have sent them some 300WSM cases to play with.

Next I will admit some ignorance. I thought a .270 bullet was truly 0.270". Didn't realize it's actually 0.277". So, as usual, Erik is 2 steps ahead of me. Agree that necking up 0.007" from 0.277" to 0.284" is likely not as risky as necking up the 6.5-284 cases (0.264") to .284" plus you avoid the cost of a die.

But, I was able to find Norma 300WSM brass for $21/20ct which is cheaper than I've seen 270WSM brass. So I'll make up most if not all the cost of the die just on the first batch of brass.

I'll keep you posted.