Top pick for most buyers: a replica of the 44.25 mm Speedmaster Co-Axial Chronograph with the correct two-register dial, because that is the version where the outside of the watch can be copied closely and the movement inside can still be judged with a few simple checks. The criteria that matter are the subdial functions at 3 and 9, the hand stack and pusher feel, the caseback and rotor finish, and the weight and spacing of the dial print. This guide covers what Calibre 9300 is, how fakes give themselves away, and which replica build suits which buyer.

What Calibre 9300 is, in plain terms

Calibre 9300 is Omega's automatic Co-Axial chronograph movement, used in the 44.25 mm Speedmaster Co-Axial Chronograph and in the Dark Side of the Moon line. It is a bi-compax design: two counters, not three.

  • A combined 60-minute and 12-hour totalizer sits at 3 o'clock.
  • Running small seconds sit at 9 o'clock.
  • The date sits low on the dial, at 6 o'clock on most references.
  • Twin mainspring barrels give roughly 60 hours of power reserve.
  • A silicon balance spring, column wheel and vertical clutch sit inside.

That list is the whole identification game. A watch sold as a Calibre 9300 Speedmaster with three registers, a central running seconds hand, or the date at 3 is not a 9300, genuine or replica.

The five-minute fake check

  1. Count the subdials. Two is correct. Three means a different movement family.
  2. Watch the small seconds at 9. It should run continuously, while the chronograph drives only the central hand and the 3 o'clock totalizer.
  3. Start and stop the chronograph. A vertical clutch engages smoothly; a cam-driven clone often shows a small stutter or a jump on the first press.
  4. Check the hand stack height. On a genuine 44.25 mm case the hands sit close to the dial; many fakes build a taller stack that reads as a shadow under the crystal.
  5. Turn it over. A genuine 9300 has a sapphire caseback with visible barrels and a decorated rotor, not a closed steel back with a stamped logo.
  6. Read the dial print. Letters should be crisp and evenly spaced, with an applied logo rather than flat, thick printing.

Option 1: Bi-compax replica with a working totalizer

This build copies the dial architecture and keeps the layout honest: small seconds at 9, chronograph totalizer at 3, date at 6.

Pros

  • Correct dial layout, so it holds up to a close look from a friend or a dealer.
  • Caseback and rotor can be finished to a convincing standard.
  • Chronograph controls are usable for everyday timing.

Cons

  • Movement architecture will not match a genuine 9300 once the back is open.
  • Power reserve is usually shorter than the real 60 hours.
  • Service and parts support depend on the maker.

Recommended for daily wear, and for anyone who wants one Speedmaster-style chrono that looks right on the wrist.

Option 2: Three-register replica sold as a 9300

These turn up often. The case is close, the bezel is close, and the dial is wrong. Most run a modified 7750-family movement, which uses a cam-and-lever chronograph instead of a column wheel.

Pros

  • Lower cost and easy to find.
  • Familiar Moonwatch look at a glance.
  • Proven movement family that most watchmakers can touch.

Cons

  • Wrong subdial count and wrong subdial positions.
  • Date often sits in the wrong place.
  • An instant tell to anyone who knows the reference.

Buy it only as a generic chronograph. It is not a stand-in for a 9300 Speedmaster.

Option 3: Quartz or slim-case replica

Pros

  • Light, thin and low maintenance.
  • Cheapest way to wear the silhouette.

Cons

  • The chronograph hand sweep gives it away.
  • Pushers feel hollow and the case proportions thin out.
  • No display caseback worth showing.

Fine as a knockaround. Wrong if the goal is a convincing 9300.

Which build fits your use case

  • Daily wear, office and weekend: Option 1.
  • First chronograph on a tight budget, no interest in the movement: Option 2, with eyes open about the dial.
  • Collecting and comparing details: Option 1 with a display back you can inspect under good light.

Bottom line

Calibre 9300 fakes fail on layout more often than on finish. Count the subdials, check where the date sits, feel the chronograph press, and look at the back. If those four things line up, you are looking at a serious build rather than a generic chrono in a Speedmaster case.