Star Si35
- Category
- Submachine Gun
- Barrel
- 269 mm
- Weight, empty
- 3.80 kg
- Introduced
- 1935
About
What it is, and why it matters
The Star Si35 is a Spanish submachine gun developed by Star Bonifacio Echeverria of Eibar and introduced in 1935. Chambered in 9mm Largo, it used a delayed-blowback, open-bolt action and fed from 10-, 30- or 40-round magazines. Unusually for its era it offered a selectable rate of fire, with a second selector lever allowing the user to switch the cyclic rate between roughly 300 and 700 rounds per minute. Saw use during the Spanish Civil War.
Built in Eibar in the Basque Country, the Si35 family was caught up in the Spanish Civil War: it was produced for the Republican side until Nationalist forces captured the city, after which output served the opposing army.
The Si35, RU35 and TN35 were visually identical and mechanically nearly the same, differing chiefly in cyclic rate: the RU35 fired at about 300 rpm, the TN35 at about 700 rpm, while the Si35 could toggle between the two. The design was reliable but unnecessarily complex and costly to manufacture.
Specification
Everything measured
IdentityWhat it is, who built it and when.
- Manufacturer
- Star Bonifacio Echeverria
- Category
- Submachine Gun
- Country
- Spain
- Status
- Discontinued
- Produced
- 1935 to 1939
DimensionsAs issued, without a magazine or an optic.
- Barrel
- 269 mm
- Overall length
- 900 mm
- Weight, empty
- 3.80 kg
ActionHow it cycles, what trips it, and what feeds it.
- Action
- Delayed blowback
- Firing mechanism
- Open bolt
- Trigger
- Single stage
- Capacity
- 30
- Magazine
- Detachable box
MaterialsEach swatch is the material itself, not a colour chosen to stand for it.
- Frame
- Steel
- Slide
- Steel
- Barrel
- Steel
- Stock
- Wood
- Finish
- Blued
BallisticsFrom the service cartridge, not a handload.
- Muzzle velocity
- 381 m/s
- Muzzle energy
- 541 J
- Effective range
- 150 m
- Rate of fire
- 700 rpm
Trajectory
What the round does downrange
Solved from the muzzle figures and the bullet. The dashed rule is the effective range on the record, and the crosses are the steps the solver returned.
No load solved for this record yetThe flight path is computed from a cartridge and a bullet. This record has no ammunition filed against its chambering, so there is nothing to solve.
Features
What it has
What the record lists as fitted, drawn from the catalogue.
Wooden stock- Selectable rate of fire
Bayonet lug
Delayed blowback action
Standing
How it compares
Each figure against the firearms of the same type and cartridge that record it, or of the same type where that cartridge has too few. Positions are read to the nearest tenth.
| Measurement | This firearm | Median | Position |
|---|---|---|---|
| Empty weightAmong 282 submachine guns | 3.80 kg | 3.15 kg | Heavier than about 80% |
| Overall lengthAmong 281 submachine guns | 900 mm | 737 mm | Longer than about 90% |
| Barrel lengthAmong 282 submachine guns | 269 mm | 213 mm | Longer than about 80% |
| Magazine capacityAmong 287 submachine guns | 30 | 32 | Holds fewer rounds than about 70% |
Answers
Questions about the Star Si35
How much does the Star Si35 weigh?
The Star Si35 weighs 3.80 kg (8.38 lb) empty.
What caliber is the Star Si35?
The Star Si35 is chambered in 9mm Largo.
How many rounds does the Star Si35 hold?
The Star Si35 holds 30 rounds, fed from a detachable box magazine.
How long is the Star Si35?
The Star Si35 is 900 mm (35.4 in) long overall, with a 269 mm (10.59 in) barrel.
Who makes the Star Si35?
The Star Si35 is made by Star Bonifacio Echeverria (Spain).
When was the Star Si35 introduced?
The Star Si35 was introduced in 1935 and discontinued in 1939.
How does the Star Si35 operate?
The Star Si35 uses a delayed blowback action, and its firing mechanism is open bolt.
Compatibility
Which parts fit this firearm
Studio
Every part that mounts on this, resolved
Not a list the maker typed out: the answer comes from the mounts this firearm exposes and the interface each part needs, so it stays right when either one changes.
- Every part that mounts on any firearm in the catalogue
- Interface standards, platforms and fit overrides
- The same answers through the API and the MCP server
Requires a signed-in GunSpec account on the Studio plan. The answer is computed per part, so it is not part of the public record.
Provenance
What the record holds
Every figure above was taken from one of these pages. The confidence reflects how much of the record came from a page a claim can be checked against.
In service
- Spanish Republican Army
- 1936
- Guardia Civil
- Spain
Provenance
Confidence in this record
80%
Stockists
Where to buy
Offers link straight to the shop. GunSpec never takes the order.
No shop has listed this firearm yet
Stock and prices come from the shops themselves. If you sell this firearm, you can list it and it appears here.
List a firearmMCP
Ask an assistant about it
The same record, reached the way a person asks for it rather than the way a program does.
Ask GunSpec
Works with
Point an MCP client at GunSpec and it answers from the catalogue rather than from memory. A free key covers the read tools.
API
The call that returns this record
The same fields, in the same units, from the same endpoint the page reads.
curl --request GET \ --url 'https://api.gunspec.io/v1/firearms/star-si35' \ --header 'X-API-Key: your_key'{ "id": "star-si35", "name": "Star Si35", "manufacturer": { "id": "star", "name": "Star Bonifacio Echeverria", "countryCode": "ES", "foundedYear": 1908, "website": null, "logoUrl": null, "description": null, "status": null, "defunctYear": null, "stateOwned": null, "makesFirearms": null, "parentId": null, "predecessorId": null, "createdAt": "2026-02-18 03:40:48", "updatedAt": "2026-02-18 03:40:48", "version": "718648e74a6528b85199425c1812d408886d97eb43af5ac2bd1086cb566a706a" }, "category": { "id": "submachine-gun", "name": "Submachine Gun", "description": "Automatic firearms chambered in pistol calibers" }, "country_of_origin": "ES", "year_introduced": 1935, "barrel_length_mm": 269, "weight_empty_g": 3800, "action_type": "delayed_blowback"}