Short answer

Almost nothing sold as a replica Speedmaster Cal. 321 contains a Cal. 321. The original is a column-wheel, horizontal-clutch chronograph that Omega used from 1957 until roughly 1968, when the cam-actuated Cal. 861 took over. Replica listings that say "321" are usually describing the reference they copied, not the movement under the caseback. What sits inside is one of three things: a Seagull ST19, a Valjoux 7750 variant, or a quartz module. Only the ST19 feels remotely like the real thing.

So the question worth asking is not "does it have a 321." It is "which movement is in it, and do I care?"

The three movements you will actually find

  • Seagull ST19. A hand-wound column-wheel chronograph with a horizontal clutch, descended from the Venus 175 tooling. Beats at 19,800 vph. The pusher click is light and crisp, and the start of the chrono hand has a small, natural hesitation. This is the closest budget match to a 321 by architecture, even though it is a different design.
  • Valjoux 7750 family. Automatic, cam-actuated, 28,800 vph. Pushers feel firmer and slightly mushy by comparison. The bigger giveaway is the layout: a 7750 puts the running seconds at 9 and often adds a day or date window that no vintage Speedmaster ever had. If the subdials sit at 6, 9 and 12 with a date at 3, you are looking at a 7750 case, not a Speedmaster case.
  • Quartz or meca-quartz. Cheap tell: the chrono second hand snaps in one-second jumps, and the subdial hands reset with a hard twitch. No sweeping motion, no pusher feel worth discussing.

Why the 321 label gets attached to everything

Cal. 321 is the famous one. It went to the moon on the early flights, it shows up in auction results that make people stare, and it has the romance that a cam movement does not. Sellers know this. Stamping "321" on a listing costs nothing and pulls in buyers who want the story more than the mechanics.

There is one honest edge case. Some higher-end builds use a decorated ST19 with a custom bridge plate and engraved lettering meant to echo a 321. It is still an ST19. The decoration is cosmetic, and if the case has a solid caseback you will never see it anyway.

Reference details to check before you buy

  • Case size. Early Speedmasters ran 38.5mm to 39.5mm. The 105.012 pushed it to 42mm. A listing that says "42mm, exact 1957 copy" is mixing references.
  • Lugs. The lyre or twisted lug profile belongs to certain references. Straight lugs on a watch sold as a 105.012 is wrong.
  • Bezel. The dot-over-90 and dot-diagonal-to-90 bezels only appear on specific production windows. A seller who cannot name which one they used usually did not check.
  • Subdial layout. 3, 6 and 9. If there is a date window, walk away.
  • Caseback. Vintage Speedmasters are solid steel. The modern 321 reissue has a display back. A replica with a display back showing a plain, undecorated movement is being honest about what it is.

How to judge it in your hand

Wind it slowly and listen. A column wheel gives a smooth, even feel through the whole wind; a cam movement gets stiffer as it loads. Press the top pusher. On a column-wheel chrono the start is a quick, clean click with almost no travel. Then hit the reset and watch the subdial hands. They should return to zero in one motion, not creep there.

Also check the pushers for side play. Loose, wobbly pushers on a fresh watch mean a cheap case, and a cheap case usually means a cheap movement.

Cost reality

A real Cal. 321 Speedmaster runs well into five figures. A replica runs a few hundred dollars. If a listing promises a newly made 321 movement for three hundred dollars, it is not a 321 and the seller knows it. What you are really paying for at that price is the case, the dial and the bezel, and that is the part worth inspecting closely.

One practical note: in the US, buying and importing counterfeit goods is illegal, and customs does seize packages. That risk exists no matter how good the movement feels.