Why mechanical fire-control computers endured

What would limit a Babbage-style mechanical computer used for naval fire control?

Mechanical fire-control tables remained useful into the 1960s and lasted longer for large guns, where replacing them required a new system that nobody had funded.

Mechanical fire-control tables remained useful into the 1960s. For large naval guns, they lasted longer because a replacement would require a new system designed from scratch. Funding that replacement was a separate obstacle from the ability to calculate a firing solution. This experience gives the Babbage-style naval computers in The Difference Engine a practical historical comparison.