Forming 243 WSSM from 300 WSM

[M_59]

I was wondering if anyone had tried this conversion or has any ideas how one would go about doing it? I see Hillbilly Brass is doing it so it must be possible one way or another.

[country gent]

I would imagine its some work. If I were to try it I believe I would size the neck down in 2-3 steps and then the shoulder. setting it to the chamber on my rifle. I would then trim to length as the case will get longer sizing it down. Also would expect to have to neck turn or ream as the neck walls will get thicker sizing down. Also plan on at least 1 annealing. I have a wildcat round that takes 300 wsm to 6.5 mm and shortens it giving basically the same case capacity as 6.5 284 in a shorter case. I anneal the cases. Push the shoulder back and neck to .270. then neck to 257 and finally to .264. Neck is close to .016 thick now but some is also the old neck. I trim to length. I then neck ream and then neck turn. and then anneal once more to remove work hardening from reforming.

[reed1911]

If you need brass, we have New Winchester .243 WSSM at 79.50 per bag of 50

[M_59]

The nearly $2 each price is why I am thinking about forming my own. I have some 300 WSM and was wondering how to go about it? Could a 300 WSM case be cut off, annealed and then a new neck shoulder formed?

[reed1911]

Yes, the WSM case can be used but it requires a lot of labor. The brass needs to be cut down, reamed, annealed, necked down in steps, annealed, and then a final trim and final ream (or final neck turn). You would be looking at about 700-800 in dies (unless you make your own) for the forming and a lot of labor time to do all the work.

[McFred]

There's a local store here with 5 x 50 bags of .223 WSSM for 37¢ per case, new production. If you're going to convert something, it's pretty easy to neck up and fireform that last 2˚ on the shoulder for the 6mm flavor. I have some FC .223 WSSM I can sell you too if you're that hard-up, M_59. I will also say that if you anneal the necks/shoulders you can get a LOT of firings on a WSSM case; they are THICK!. I've got a box of 50 approaching 30 reloads (mostly neck-sizing) without loose pockets or split necks.

[M_59]

Thanks for the offer. I will keep that in mind.