Reading Glock part numbers and generation markings

A Glock tells you what it is if you know where to look, and so do its parts. The slide carries the model, caliber, country and generation; the ejector, connector, follower and recoil assembly carry numbers or marks that identify them; and Glock's own spare parts carry SP numbers that let you order exactly what came out. This guide reads each marking so you can identify a pistol from across a counter and order the right part the first time.

The slide

The left side of the slide carries the Glock name and the model, for example GLOCK 19, with the caliber, 9x19 or .40 or 10mm AUTO or .45 AUTO. Gen 4 slides add Gen4 after the model and Gen 5 slides add Gen5; Gen 1 to Gen 3 slides carry no generation mark, so you identify those by the frame. The right side carries the serial number and either AUSTRIA or USA for the place of manufacture, with Austrian proof marks on the Austrian pistols. MOS pistols say MOS after the model on the slide.

The frame

The serial number sits on a steel plate molded into the frame ahead of the trigger guard on every generation from Gen 2 and matches the slide and barrel on a factory pistol. Generation without a slide mark: pebble grip and two pins is Gen 1; checkered grip, three pins from about 1990, is Gen 2; finger grooves and a rail is Gen 3; rough texture, large magazine catch and a backstrap cut is Gen 4; no grooves, flared well and two pins is Gen 5. The frame also carries a molded date code inside the magazine well or under the grip on many pistols, which Glock's service department can decode.

The barrel

The barrel hood carries the serial number and the caliber. Gen 5 Marksman Barrels are marked as such on some production and are identifiable by the conventional rifling visible at the muzzle and the target crown. Aftermarket barrels carry the maker's mark and caliber and often a model designation.

The ejector

The number on the ejector blade, visible through the ejection port with the slide locked back, identifies the trigger housing: 336 or 30274 for 9mm through Gen 4, 1882 or 28926 for .40 and .357 SIG, 8196 for 10mm and .45 ACP, 47021 for Gen 5 9mm. It is the fastest way to confirm a pistol's caliber family and generation when the slide is off.

The connector

Look at the connector in its slot on the right of the housing: no mark is the 5 pound original, a dot is the 5.5 pound, a minus is the 4.5 pound and a plus is the 8 pound. Gen 5 connectors are their own part. Aftermarket connectors carry the maker's mark.

Magazines and followers

The magazine body carries the caliber and capacity on the back with witness holes, and a Gen 4 or later body has a catch notch on both sides. The follower carries a number that identifies its caliber and revision; Gen 5 9mm followers are orange. A magazine with a single notch is pre-Gen 4; one with an extended front lip on the floorplate is Gen 5.

The recoil spring assembly

Gen 4 and Gen 5 dual assemblies carry a number on the rod's head that identifies the revision; early Gen 4 assemblies went through several, and the current ones are the ones to have. A Gen 3 single-spring assembly is unmarked polymer.

Trigger bar, striker and extractor

The trigger bar is unmarked but identifiable: a wide cruciform means the large frame, a Gen 5 bar has a different cruciform and ramp, and a slimline bar is narrower. The striker is unmarked; Gen 5 strikers have a different safety cut. Extractors are identified by the loaded chamber indicator bump, present on Gen 3 and 4 LCI extractors and absent on early ones, and the Gen 5 extractor by its shape.

Glock SP part numbers

Glock's spare parts carry numbers of the form SP followed by five digits, printed on the factory packaging and listed in Glock's parts catalog; SP05300, for example, is a 9mm trigger housing with ejector. When a listing here gives an SP number, it is Glock's own number for that part, and it is the most exact way to order a replacement. Aftermarket parts carry the maker's numbering; we list the Glock part they replace.

Aftermarket markings

Aftermarket slides, barrels, triggers and connectors carry the maker's name or logo and usually a model or generation designation, and reputable makers mark the generation fit on the part itself, not only the box. A slide marked G19 Gen 3 fits a Gen 3 or Gen 4 frame; one marked Gen 5 fits only Gen 5. An unmarked aftermarket part with no maker's name is a part whose origin and fit you cannot check, and the safest thing to do with it is replace it with one you can.

Putting it together

To identify a pistol: read the model and caliber on the left of the slide, the generation from the slide mark or the frame, the country from the right of the slide, and confirm the housing by the ejector number. To order a part: note the model, generation and caliber, find the part in slide parts or frame parts, and match the generation and any number on the listing. The barrel guide covers barrel marks and fit, and the wear schedule says when each part is due. Browse Glock parts; they ship to your door.

General information, not legal advice. Current as of September 2026. Laws change; check the official source before you act.