Since 1945, AYA has manufactured more than 600,000 shotguns of all types and grades.

Until 1995, the guns were assigned serial numbers chronologically, regardless of grade or type. In 1995, the Spanish proof house implemented a new system of serial numbers. Now, each gun has a serial number that consists of four sets of digits, separated by a hyphen. Each set of digits has a distinct meaning.

The first set is the gunmaker code. The second set designates the type of firearm. The third set, which may run to three or even four digits, is the chronological number assigned by the gunmaker in a given year, and the fourth set of two digits shows the year of manufacture.

For example, AYA’s gunmaker code is 16, and the code for a shotgun is 03. Therefore, the serial number 16-03-241-98 shows that this is a shotgun, made by AYA, and that it was the 241st gun produced in the year 1998.

From 1927 until 1994, the Spanish proof house employed a system of date codes which were stamped on most (but not all) firearms produced in Spain. These code numbers or letters were stamped on the action flats, or the barrel flats, of the firearm along with the proof marks.

Date codes, 1927 - 1944:

(The codes from 1995 onward were assigned but never used)

Weapon Codes, Effective 1995

The second pair of digits in each new serial number indicates the type of weapon. This allows someone looking only at the serial number (for example, in a list of records) to know immediately what he is dealing with.