HANG ON A MINUTE...HAD A REPORT OF LESS THAN ACCEPTABLE FUNCTION...GOING TO RE-CHECK WITH MORE THAN ONE MAG TO GET BETTER RESULTS...LETS WAIT AND SEE.
I just got one of these RZE Unimags today...going to test it with the 450b and 30RAR to see if it works with them. Company says it is currently testing their Unimag with several other calibers, so an expanded list that it works with should be forthcoming. Links to the info on them are below. I'll try this mag with the 450b and 30RAR probably Monday...I'll let you know what happens. I suggested to RZE that they check out these calibers themselves...they should at least be looking at the 450b, since they list the 458 Socom as compatible...similar dimensions, etc. I'll find out for myself in a day or two...
http://ross-zheng-engineering.myshopify.com/
http://ross-zheng-engineering.myshopify.com/pages/demo
I took mine apart, and it has a very clever two-piece, spring-loaded, articulating follower that apparently compensates for the varying case body profiles. The mag spring and base plate are standard AR style. The mag body is SS, I think (non-magnetic and sounds like steel). The mag body looks standard, but if you look closely there are subtle shape changes just at the top of the long dimension where the topmost cartridge sits. The feed lips look surprisingly far apart, but that does not seem to be a problem. The 450b rounds double-stack as do the 30RAR rounds, with eleven rounds fitting in the mag for both (not surprisingly.)
More later...