Omega Aqua Terra Railmaster is one of the first Omega Railmaster reissues from the early 00s. The watch features no-date 2403 movement and 3-6-9 dial present in the earlier references. The thing to note is that the Aqua Terra Railmaster is not an antimagnetic watch in the spirit of Eberhard Scientigraph, Rolex Milgaus, IWC Ingeniur or the original Omega Railmaster. Instead, as part of the Aqua Terra lineup, the 2504.52 Railmaster was perhaps meant to compete with Rolex Explorer.

The Aqua Terra Railmasters are defined by no date 3-6-9 dial, painted super luminova plots, screwdown crown and co-axial movement. The watches offer 150m water resistance making them durable companions to office dwellers, commuters and downtown mall spelunkers .

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Basic Information

Manufacturer	Omega
Reference	2504.52
Movement	2403 (ETA 2892-A2)
Diameter	36,2mm
Thickness	11mm
Lug to lug	44mm
Lug width	19mm
Material	Stainless Stee
Water Resistance	150m

References

The 36mm Aqua Terra Railmaster was released during time when Omega lineup was based on the more is more principle. Similarly to the Planet Oceans, the Aqua Terra Railmaster was released in multiple configurations from 36mm to 49mm. Of these, the 39mm variant is the most popular and easily found. There has been discussion that the 41mm would be the rarest, but they seem to be available at any given moment unlike the 2504.52 or 2804.52 which show up few times a year.

Reference	Size	Lug Width	Details
2504.52	36mm	19mm	1575/899 bracelet
2804.52	36mm	19mm	Leather strap
2503.52	39mm	20mm	1574/898 bracelet
2803.52	39mm	20mm	Leather strap
2103.52	39mm	20mm	Yellow gold, yellow gold bracelet
2603.52.37	39mm	20mm	Yellow gold, brown leather strap
2603.52.31	39mm	20mm	Yellow gold, black leather strap
2502.52	41mm	21mm	1573/887 bracelet
2802.52	41mm	21mm	Leather strap
2806.52.37	49mm	24mm	Leather strap, Manual wound
221.53.49. 10.01.001	49mm	24mm	Rose gold, leather strap, manual wound
221.53.49. 10.01.002	49mm	24mm	White gold, leather strap, manual wound

If you’re “A Big Watch Guy” the 49mm Railmaster could be a good alternative IWC Big Pilot. In a way, the most interesting reference is the 18k 2103.52 with the 18k gold bracelet. I don’t fancy owning one, but it’d be amazing to see it in person one day.

Bracelets

The bracelet features integrated clasp without any micro adjustments. The bracelet is a typical pin & collar bracelet of the era. The bracelet is robust and serviceable as pins take most of the wear and they can be replaced during the service. The downside is that for amateurs the bracelets can be difficult to adjust and it is easy to bend pins and lose collars.

Braclet / Endlink	Lug Width	Buckle
1575/899	19mm	16mm
1574/898	20mm	17mm
1573/887	21mm	18mm (?)

For those who suffer from swelling, the bracelet may not be optimal as there is no micro-adjustment. Another issue is getting it properly fit as the size is controlled with half-links. As for the 2504.52, the 19mm to 16mm taper is proportioned and relatively standard and the bracelet is very comfortable.

For perfectionists and people who suffer from OCD, the bracelet design makes it nearly impossible to center the hidden clasp. This may be a serious downside depending on the mental condition of the watch enthusiast.

Straps

Field watches and nato straps go together like salt and pepper. The 2504.52 is no exception. For people who can’t live with a cheeky springbar, the 19mm lug width may be difficult to digest. However, if you take the peeking spring bar as a stylistic element, the Railmaster Chronometer can be worn with just about any 18mm Nato.

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Another option is leather. I have yet to purchase a 16mm Omega Deployant clasp, but I’m planning to do so and get a quality leather, sailcloth and canvas for change.

Dial and Hands

The 3-6-9 dial is a throwback to the original Railmaster from 1950s. Aside from green super luminova, the Railmaster Chronometer has more text on the dial. The defining feature of the no-date dial is symmetry and simplicity. The dial of the 2504.52 is about the same size as 2201.50. This makes it a very good companion to the 42mm Planet Ocean of the same time. The 2503.52 has a slightly larger dial than 2201.50, which may look out of place next to such imposing dive watch.

With the hands, there comes a major difference to the original railmaster. The original Railmaster has Ranchero style hands with Arrow hour-hand whereas the Aqua Terra Railmaster has a regular hour hand and arrow minute hand. This difference is inherited from the Aqua Terra line-up, which still uses this configuration even today.

Movement

The watch is powered by the 2403 movement, which is a no date version of the cal 2500. Just like the cal 2500, due to the early issues with the co-axial escapement, the movement received an upgrade with lower beat rate. It is not a big surprise to anyone that the movement feels and winds exactly like its date sibling, the cal 2500, but without the date adjustment. Crown action is robust and very tool-watchey. The see-through case back is a nice touch and the rhodium plated movement is beautiful.

The 2504.52 is a late addition to the family. The 39mm and the 41mm versions can be found with both movement types 2403A and 2403B. However, all of the examples of the 2504.52 that I have tried to buy have been with 2403B movement with 84xxxx serial. If somebody knows whether the 36mm Railmaster came with a 2403A, I’d be interested to know and update this post.

2504.52 Seen in Wild

Reference	Serial	Movement	Sold	Seen on	Price
2805.52	847	2403B		Chrono24 Dec 2022 (Norway)	3600 EUR
2804.52	???	???		Chrono24 Aug 2022 (Germany)	3200 EUR
2504.52	84780XXX	??		Chrono24 Aug 2022 (USA)	4 704 EUR
2504.52	84644XXX	??		Chrono24 Aug 2022 (USA)	4805 EUR
2504.52	???	??	??	r/watchexchange, May 2022	4200 USD
2504.52	84762XXX	2403B	7th of April 2011	r/watchexchange, May 2022	5000 USD
2504.52	84762XXX	2403B	7th of April 2011	Yahoo Auctions Japan 16/3/2022	440 000 JPY
2504.52	81712850	??	??	Chrono24, Germany, 14/11/2021	3750 EUR
2504.52	81699609	??	2007.1.4	Yahoo Auctions Japan 17/10/2021	220 000 JPY
2504.52	???	??		Chrono24, Czech Republic	4300 EUR
2504.52	84699791	??	October 26th, 2010	Chrono24, USA 24/7/2021	4999 USD
2504.52	???	??		Chrono24, Singapore 11/8/2021	3755 USD
2504.52	84697953	2403B	2012	Chrono24, Usa 6/8/2021	4513€
2504.52	84643XXX (mine)	2403B		Yahoo Auctions Japan 25/7/2021	300000 JPY
2504.52	Unknown	Unknown		Chrono24 (Japan)	2735€
2504.52	8478XXXX	2403B		Watchuseek 30/10/2020	4250 USD
2504.52	81699XXX	2403B		Omegaforums 30/8/2020	4150 USD

Conclusion

The 36mm Railmaster Chronometer is an interesting watch:

• It can be used to make a poor man’s late 00s trilogy.
• It is an obscure alternative to Rolex Explorer.
• It is rare and worth collecting / hunting.

Personally, I find the early co-axial movements interesting and the looks of 2504.52 appealing. It makes an excellent everyday watch and a perfect companion to the 2201.50, which I also like.

In case of errors, please reach me out with DMs. I’d like to correct them.