Does anyone make a floorplate or bottom addition to fit the CZ 550 Magnum in .416 Rigby, which would allow 4 rounds in the magazine, that a mechanically challenged person can fix to his rifle?

When my CZ was built for Heritage Arms, the smith remilled the follower ... just holds 4 down. I don't think it has an new floor plate.

It doesn't take much. Just lower the critical surfaces of the follower by </=0.1". A thinner follower will do it, and likely a stronger magazine spring, as the factory CZ springs are often weak and prone to breakage. Lengthening the stamped sheetmetal box by that same amount would also work, but then the bottom metal protrudes from the factory stock, and a new stock would be needed. The CZ already has a pocket plate though not very pronounced. Adding a deeper pocket in the floorplate would be more expensive, but might allow 5 Rigby's down.

I thought they got 4 down to start with.

500NE,
Since my German language abilities are basically non-existent, could you post a link to a site where I can order a Frankonia catalogue?
I suppose that if I then called them up to order stuff with my credit card they would help me overcome the language barrier.
Thank you,
JCN