To get this back on topic, I have a ZG47 that some joker rebarreled once already. In fooling around with it, it will take a 375 in the top of the mag box, and will pick it up and feed it (part-way until it stops in the current 7mm bore) and will eject it. That size cartridge can be inserted in the magazine by backing it in under the rear receiver ring and then pushing it onto the follower. It almost seems that it could be converted to 404 by opening the bolt face, and increasing the length of the box by 0.15 or so, and of course rebarreling. Does anyone have a ZG47 rechambered in 404? Any thoughts on this?
I'm not a gunsmith. But, from what I've learned, that may not be the best way to go. Getting a .404J to feed smoothly, from what I understand, can be a problem. You'd have to have a good bit of work on the mag and maybe some work on the rails. The bolt face, extractor work would probably be the least trouble of all.
In the end, you're going to spend some serious money with no guarantee that you'll be happy with this project.
Find a gunsmith who does DG round conversions and ask about the feasibility of that conversion.
For my .404J build, I started with a .300 Ultra Mag Stainless Classic M-70. The .404J is the parent round for the RUM's. They have a slightly rebated rim, so the RUM bolt face and extractor will have to be opened up slightly to accommodate the slightly larger .404J rim. The mag box and rails are suitable for the .404J case and shouldn't need much, if any, work.
Good luck.
DF
