“As a production class shooter, I read that ‘magazines may not be retained through magnetic means.’ Does that include the ‘load and make ready’ magazine?”
While you may have a magazine on a magnet outside the course of fire, the course of fire starts with “Make Ready” (8.3.1) and ends with “Range is Clear” (8.3.8) So if you got the Make Ready command and the magazine was on the magnet, you would be moved to Open Division (per 22.214.171.124). IF the magazine were off the magnet, and in your hand at “Make Ready,” then you would be OK, but in reality, most people don’t do that, and as you state in your example, loading from the magnet would be during the course of fire and would be illegal for that division. Likewise, unloading to the magnet, prior to the “Range is Clear” command, would also be a violation. For more info, read this post.