Railgun projectile shielding and the case for larger shells

How would a railgun protect sensitive projectile electronics from its magnetic fields?

The answer proposes heavy shielding and argues that its space penalty could favor larger shells when a useful land-attack payload is required.

Heavy shielding is proposed as protection for sensitive electronics exposed to a railgun's magnetic fields. It would occupy a substantial proportion of a small projectile. The discussion distinguishes air-defence uses that might employ a solid projectile from land attack that requires useful payload inside the shell. In the proposed comparison, a larger shell could devote a smaller proportion of its volume to a protective layer of a given thickness. The suggested 9.2-inch and possibly 12-inch weapons remain speculative possibilities rather than an established development program.