A brief history of the Star Modelo Militar 1920 pistol.
First a brief note on reference material for Star Pistols. The Star factory had a habit of changing characteristics on it's firearms without changing model names. Therefore you may find conflicting information than given here, and your Star may exhibit characteristics not mentioned here.
The Star Modelo Militar 1920 was produced by the arms maker Star Bonifacio Echeverria S.A. in 1920 and 1921.
In 1920 the Guardia Civil was looking for a new standard sidearm and word went out to the Spanish arms making industry for submissions. Senior Bonifacio Echeverria looked to the Sam Browning designed M1911 pistol as a starting point a developed the Modelo Militar 1920 chambered in 9mm Largo. This design was selected by the Guardia Civil (Civil Guard) as its new standard sidearm and production commenced.
Shortly after adopting the pistol, the Guardia Civil decided that they were not completely satisfied with the design. They felt that the slide mounted safety was not appropriate for a service pistol. With this in mind, the Star designers went back to the drawing board and made changes, moving the safety to the frame and adding a grip safety while they were at it. This became the Star Modelo Militar 1921.
The Star Modelo Militar 1920 has been out of production for 80 years now and there are no known remaining stocks of new parts. Used parts are rarely encountered but my be available from a variety of sources.
The safety of this pistol is mounted on the slide and rotates down
for safe and up towards the rear of the pistol for firing. It rotates a
small firing pin 'extension' out of alignment with the firing pin
itself and precludes the hammer contacting the firing pin. It does not
however inhibit normal trigger or hammer functions. It is very hard to
manipulate this safety with the hammer in the down position and a small
'quarter cock' notch is provided for this.
The slide does not have cocking serrations as are common on most semi-automatic pistols of today. The rear of the slide is 'relieved' between the safety and the ejection port giving the firer an area to grip the slide and charge the pistol. This is a workable system and gives the pistol's slide a distinct appearance.
Many people mistake the 'S.A.' in the Star name and stamped on the slide of Star pistols to be a model designation. I constantly see Star pistols listed on online auction sites as "Star Model S.A. 9mm pistol." These normally turn out to be Star Modelo A, B, and Super pistols. The 'S.A.' is actually a Spanish abbreviation for 'Sociedad Anónima', the English equivalent would be 'corporation' or 'incorporated' Determining the correct model of later Star pistols is achieved by looking at the bottom of the butt. The model designation and serial number are stamped there. However, on the early Stars there is no model designation on the butt of the pistol. The collector must determine the model designation based on features present. Interestingly though, this pistol has the serial number stamped onto the butt of the pistol like later Star pistols. The Modelo 1921 pictured on this site does not, however, have this information on the butt of the pistol. I do not have information on butt markings on the Modelo 1922, but all later Star pistols I have seen have the serial number and model designation stamped on the butt.
Spanish firearms produced after 1926 can be dated with the Year of Proof Codes. The pistol should have been proofed shortly after manufacture, and surely not before. This is normally located on the left side of the frame forward of the slide stop. Pistols produced before 1927 can only be dated by model production dates. However, exceptions do exist. I have one Spanish pistol manufactured in 1925 that is stamped under the left grip panel 'Eibar 1925', if you are truly interested in the provenance of your old Spanish steel, it is advisable to carefully disassemble the pistol to look for additional markings. Caution must be exercised however to not damage or lose any irreplaceable parts. There are lots of small pins and springs in these pistols.
When 9mm Largo ammunition was hard to find in quantity shooters regularly fired other cartridges such as the 9mm Luger, 9mm Steyr, 9mm Browning Long, etc in their 9mm Largo firearms. Many dealers and distributors also claimed the firearms would fire all of these and more. This however is not a prudent practice to engage in. The Star Modelo A, like all pistols firing straight walled cartridges, headspaces on the mouth of the cartridge. When a cartridge shorter than the 23mm of the 9mm Largo is used, the cartridge case cannot headspace against the end of the chamber. This leaves only the extractor to hold the cartridge case against the breechface allowing the firing pin to impact the primer. This causes excessive wear and stress on the extractor, too much freebore (the distance from the bullet to the beginning of the rifling), and scoring of the chamber walls. The result of these abnormalities can result in broken/misshapen extractors, poor accuracy, and the inability to chamber and extract correct size cases.
The use of cartridges that produce too much chamber pressure is also discouraged. Yes, the .38 Super and 9x23mm Winchester will chamber in most 9mm Largo firearms, and if they will chamber they will fire. The metallurgy and design of the Modelo 1920 were not developed to handle the pressure of these rounds. Use of these type cartridges in the 1920 risks damage to the pistol and possibly yourself through a ruptured chamber, fractured slide, or fractured frame.
Ammunition in 9mm Largo is now available from a number of sources. Surplus ammunition is now coming into the country in shootable quantities and is available at some gunshops, many gunshows, and via mailorder. Factory new 9mm Largo ammunition is being made by CCI in their Blazer line (product number 3513) with a 124g Gold Dot Hollow Point bullet. If you reload RCBS makes dies in 9mm Largo (product number 56665), these are not a normally stocked item and require special order. You can also utilize 9x23mm Winchester dies to reload 9mm Largo, the exterior case dimensions are almost identical. Starline also produces virgin 9mm Largo brass for reloading. Gone are the days of manufacturing cases out of .223 Remington (done that, not fun), 9mm Winchester Magnum (done that, much easier) or other cases.