That 585 belted case (from the left next to the 06) has same bolt face as 505Gibbs and will fit into unmodified CZ550 magnum bolt action. It will feed from a staggered magazine just like the gibbs in the CZ. Looks and works like a scale up 458winmag/Lott just fatter. And the same idea as the 500 A square. The Lott and 500A2 two of the modern best big bores. The 585HE makes three. A very clean and simple design, with no rebate, no problems at all. Perfection. The 577/585 handles some really big bullets and wild heavy loads or can still be loaded in at a practical level for a realistic hunting rifle with 577NE plus loads. That practical option, without a muzzle brake or 16-18 pound gun weight seems a real plus to me.

It is IMHO, the best in class, best of all the over 50 designs. No compromise and quite practical if you can say that about any over 50.

Between 50 and 58 caliber there are only odd ball diameters and over 58 will not fit properly in the CZ550, or requires major rebated rim and single column feed. The 58 bore is simply the best fit.

Just an opinion, but I am big fan. IMHO - Ed really has a potential winner in this one.