Forming 300 win mag brass

[bk09]

Recently got a new CZ 550 Ultimate Hunting Rifle and my Vortex Viper PST 4-16x50 FFP MRAD is soon to be in. Only problem is finding the brass for it. I have exhausted all my sources of finding this brass locally and online, I just finished going through over 10 pages of results on Google and EVERYBODY is out of stock. But I have come across the Hornady Basic Belted Mag brass to form with http://www.hornady.com/store/Belted-Mag-Basic-Family-Cases/ . Some more searching has given me mixed results for forming this to 300 win mag. I don't see how it should be a problem if I use the basic method of running into the die partially and then trimming to a little and keep going til I get it right. Any input would be great and I would be interested if anybody has tried this with any caliber in the belted mag family. And buying factory ammo is out of the question, I would rather wait for brass to come in stock versus paying top dollar for quality factory ammo.

[358156hp]

The biggest concern will be neck thickness after trimming. You'll likely need to turn the case necks to keep pressures in line. I do see that Midway has 300 H&H brass in stock, as will most suppliers. The H&H is the actual parent case of the 300 Win Mag, and would likely be easier to size down, and shorten, but you still might have to turn the necks. As always, use caution with published starting load data and be prepared to make adjustments as needed. 7mm Rem Mag & 338 Win Mag brass is all significantly shorter than the 300 brass, but could probably be fireformed and used in a pinch, but the necks would be pretty short.

[unfy]

Older thread, you've prolly already done the deed... but anyway...

Size down instead of size up if you can.  It's better to turn case necks than to have thinner walls.

And yeah, be prepared to turn your necks and accordion some cases.  Go nice and slow, remove case lube to avoid dents, etc.  Similarly, as 358156hp said, be careful when starting out with load data.  I'd prolly start 5% under the starting load for the first fire (maybe even 10% and check for barrel obstruction etc).  If the case you're sizing from is thicker or thinner, load stuffs will all be a concern.

Hope ya got a concentricity gauge, too.