ED at AHR called today and they now have single stack mags available for the CZ550. This will allow you to get difficult cartridges like the 505 Gibbs and UP to feed flawlessly. They are not cheap at $495 each but for a 500jeff,505Gibbs or especially a .600 OK this is the way to go! Schuler proved this nearly 100 years ago and it's still true. I have been waiting for this for my lightweight-10lb .600OK for awhile. Move fast folks he only has about 25 sets available!!-Rob

Robgunbuilder,

do these stack 2 or 3?

Sometime back you mentioned that for the cz550 action the middle round of 3 for the 505 gibbs did not feed and i am curious if you figured out why (i thought since the 416 rigby does 4 reliably, why not the gibbs). Thanks for any info.

rgds,

steve

Rob,

Does the same mag work for 600 OK, 505 Gibbs and 500 Jeff? Does it need to be adjusted for the different dimensions of these 3 cartridges?

According to ED, the new SS mag box should work for everything. It's supposed to hold three down too. In my opinion a new follower may be required for the different calibers , but thats it.
Steve 505, I think your refering to the 500 AHR or 500 Jeffery not the 505 Gibbs. The CZ mag box doesn't have the correct width for three rounds to feed properly. You can stagger the rounds in the magbox and kinda get it to work, but I would not stake my life on it.-Rob

This is definately the way to go for any of the larger calibers. I've got one on my 600 OK and it works flawlessly and would need no modification for any case the diameter of the 416 rigby up to the 600 Ok. I doubt a new follower would even need to be made. Ed put a lot of time and money into this design and it just plain works. I'm getting a few for some on going guns I'm building and to have a one or two on the shelf for the next project I can't do without.
John