OK, you get a 550 sizer die with a .474, .510 and .550 expander ball. Then dip your case necks into some graphite powder. Then expand the necks up in 3 steps.

Or buy some 550 Mag factory brass from QUality Cartridge.

you ask jeffe, very nice, to make you an expander mandrel... i took 416 w to 550 in one pass.... and lost ONE of 50 cases

jeffe

Is there any company that makes bullets in caliber .550??
Does the quality cartridge have a website?

OK, the 550 Magnum home page is the following:

http://hometown.aol.com/goldcoins1/myhomepage/index.html

There are 2 versions:

550 Magnum, which fits in the CZ550 action with little modification.

550 Express, which fits in a Mauser 98 action.

Quality Cartridge is here: http://owlnet.com/quality/
The 550 Mag brass is not on their site so you have to email them with an order.

Hawk is currently making 550 Mag bullets: http://www.hawkbullets.com/
If you order the bullets, Hawk will make them. Hawk bullets would be great for mooses. Others, including Barnes and Woodleigh are considering making .550 bullets.

Dies from CH4D: www.ch4d.com

Barrels from Michael Scherz at www.gilarivergunworks.com

The 550 Mag offers you the easiest really big bore conversion, and it leaves you with a controlled feed mauser or mauser-style action, instead of one of those flaky Weatherbys. You will also get greater magazine capacity by avoiding the Wby Mark V action.