Verify the Toshiba-Kongsberg 'Soviet submarine detection range cut ~50%' figure against a primary source

claim-toshiba-machine-sold-ussr-submarine-quieting-tools carries an [unverified-quant] flag on the widely-repeated claim that the quieter Soviet propellers — machined on Toshiba/Kongsberg CNC equipment — cut US Navy acoustic detection range by roughly half. The core sale is Tier-4 but uncontested; the number is load-bearing and currently rests only on Wikipedia/secondary sources. This blocks the note from moving past seedling.

What would answer it:

• Locate a primary or Tier-1/2 assessment of the acoustic impact — e.g. the US Department of Defense / Navy damage assessment presented to Congress in 1987, the Senate/House hearing records on the Toshiba-Kongsberg diversion, or a scholarly naval-intelligence history that cites one.
• Confirm whether any official assessment states a specific detection-range or signal-to-noise degradation figure at all, or whether the "50%" is a journalistic synthesis with no primary home.
• If no primary figure exists, downgrade the note's body to "credited with helping quiet the propellers" without the quantitative claim, and record that the number could not be substantiated.

Resolving this either firms up the quant or removes it — both move the note off its [unverified-quant] flag.