Short answer
Top Gun Mission 45.5 is seller shorthand for a pilot chronograph with a 45.5 mm case, a black case, and a black dial with white numerals. IWC does not list a 45.5 mm Top Gun reference. Its catalog shows 44.5 mm for the Pilot's Watch Chronograph Top Gun and 46.2 mm for Big Pilot Top Gun models. Treat 45.5 mm as a seller measurement, not a factory spec. Ask for a caliper photo of the case and the lug to lug number before you pay.
Numbers that decide fit
Three measurements matter more than the dial photo.
- Case diameter: 45.5 mm. Large for a pilot watch. It reads oversized on wrists under 17 cm (6.75 in).
- Lug to lug: 52 mm to 54 mm on this case shape. This sets how the watch sits across the top of the wrist.
- Thickness: 15 mm to 16 mm on automatic chronograph builds. It sits high under a shirt cuff.
Case material
Genuine Top Gun cases use black zirconium oxide ceramic or Ceratanium, an alloy of titanium and ceramic. Ceramic holds its color and resists scratches. It chips on hard impact and cannot be polished. Replica cases are PVD coated steel, ceramic coated steel, or solid ceramic at the top tier. A magnet test does not separate them. Ceramic is non-magnetic. Coated steel is weakly magnetic. Look at the caseback edge and the lug tips, where coating wear shows first.
Movement types
Two movement families appear in this case size. Automatic 7750 style movements run at 28,800 vibrations per hour, which is 8 beats per second. The sweep hand moves in small steps, not one jump per second. The day and date window sits at 3 o'clock on most builds. Quartz versions tick once per second and need a battery every 1 to 3 years. A mechanical chronograph should start, stop, and snap back to 12 with no lag. Test that in person or ask for a video of the reset.
Water resistance
Listings claim 30 m to 100 m. ISO 22810 treats a 30 m rating as splash resistance only. Do not swim with a replica unless a watchmaker pressure-tests the case and the gaskets. The crown must screw down clean. A cross-threaded crown tube is the most common leak path on this case design.
Before paying
- Caseback: engraving depth, reference text, screw-down or snap fit.
- Crown: threads engage without grinding, winding feels smooth.
- Chronograph: start, stop, reset to 12.
- Strap width: measure at the lugs. Sellers list 21 mm, 22 mm, and 24 mm for the same case.