What age is Winchester cannon 10 gauge serial number 229?
That number is not a serial number.
The link above no longer works and I am not the original person responding to this question. A better answer, than a dead link, was provided by a person whose gunbroker forum handle is "iron jockey". I've summarized his post as follows:
The Winchester 98 Cannon was produced for sale by Winchester from 1903 to 1957(8). The only cannons that were truly serialized were those destined for foreign sales. The 3 digit numbers are actually assembly numbers so that barrels could be matched to trunion mounts after bluing (or other production processing) that would separate these components. After the assembly numbers reached 999 they rolled back to 001.
From 1903 to 1907 the barrel muzzle diameter was 1 inch. In 1908 the muzzle was increased to 1.25 inches. During the period, from 1903 to 1907, it is believed that Winchester sold less than 1000 cannons. If your cannon has a 1 inch muzzle then the 229 number reflects the 229th cannon to roll off the production line between 1903 to 1907 (probably 1903 or 1904 time frame). If your cannon has a 1.25" muzzle then the best you can do is know it was made between 1908 to 1958.