CMMG Mk3
- Category
- Battle Rifle
- Barrel
- 406 mm
- Weight, empty
- 4.08 kg
- Introduced
- 2014
About
What it is, and why it matters
The CMMG Mk3 is an AR-10 / SR-25-pattern semi-automatic battle rifle chambered in 7.62x51mm NATO, introduced in 2014. It uses a direct gas impingement operating system with a billet 6061-T6 aluminum receiver set, a 416 stainless steel salt-bath nitride barrel, and an RKM15 KeyMod free-float handguard. Marketed in carbine-battle-rifle (CBR) and 3-Gun (3GR) trims, it feeds from SR-25/DPMS-pattern .308 magazines.
CMMG launched the Mk3 .308 platform and the Mk47 Mutant (an AK-magazine-fed AR) in the same banner year of 2014; the company itself began in 2002 in an outbuilding on the Overstreet family farm in Missouri before growing into a major AR maker.
Higher trims ship with a Geissele SSA two-stage trigger; base models use a CMMG single-stage mil-spec trigger. Overall length is variable due to the Magpul ACS-L collapsible stock. Muzzle velocity and effective range are not manufacturer-published and reflect caliber-typical values.
Specification
Everything measured
IdentityWhat it is, who built it and when.
- Manufacturer
- CMMG Inc.
- Category
- Battle Rifle
- Country
- United States
- Status
- In production
- Produced
- 2014
DimensionsAs issued, without a magazine or an optic.
- Barrel
- 406 mm
- Weight, empty
- 4.08 kg
- Weight, loaded
- 4.54 kg
ActionHow it cycles, what trips it, and what feeds it.
- Action
- Gas operated direct impingement
- Firing mechanism
- Hammer fired
- Trigger
- Two stage
- Capacity
- 20
- Magazine
- Detachable box
MaterialsEach swatch is the material itself, not a colour chosen to stand for it.
- Frame
- Aluminum
- Barrel
- Stainless steel
- Stock
- Polymer
- Finish
- Hard anodized
BallisticsFrom the service cartridge, not a handload.
- Effective range
- 800 m
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.
Features
What it has
What the record lists as fitted, drawn from the catalogue.
Direct gas impingement
Rkm15 keymod free float handguard
Sv muzzle brake
Salt bath nitride barrel
Magpul acs l collapsible stock- Free float barrel
Billet aluminum receiver
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 86 7.62x51mm NATO battle rifles | 4.08 kg | 4.30 kg | Lighter than about 70% |
| Barrel lengthAmong 87 7.62x51mm NATO battle rifles | 406 mm | 458 mm | Shorter than about 90% |
| Magazine capacityAmong 87 7.62x51mm NATO battle rifles | 20 | 20 | Near the median |
Answers
Questions about the CMMG Mk3
How much does the CMMG Mk3 weigh?
The CMMG Mk3 weighs 4.08 kg (8.99 lb) empty and 4.54 kg (10.00 lb) loaded.
What caliber is the CMMG Mk3?
The CMMG Mk3 is chambered in 7.62x51mm NATO.
How many rounds does the CMMG Mk3 hold?
The CMMG Mk3 holds 20 rounds, fed from a detachable box magazine.
How long is the CMMG Mk3?
The CMMG Mk3 has a 406 mm (16.0 in) barrel.
Who makes the CMMG Mk3?
The CMMG Mk3 is made by CMMG Inc. (United States).
When was the CMMG Mk3 introduced?
The CMMG Mk3 was introduced in 2014.
How does the CMMG Mk3 operate?
The CMMG Mk3 uses a gas operated direct impingement action, and its firing mechanism is hammer fired.
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.
Provenance
Confidence in this record
72%
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/cmmg-mk3' \ --header 'X-API-Key: your_key'{ "id": "cmmg-mk3", "name": "CMMG Mk3", "manufacturer": { "id": "cmmg", "name": "CMMG Inc.", "countryCode": "US", "foundedYear": 2002, "website": "https://cmmg.com", "logoUrl": null, "description": null, "status": null, "defunctYear": null, "stateOwned": null, "makesFirearms": null, "parentId": null, "predecessorId": null, "createdAt": "2026-02-11 23:44:38", "updatedAt": "2026-02-18 03:43:43", "version": "a7e68de40df3e6e52ce7309f32c551e46f69ca644a4955a2de5291d2bfbf7a0b" }, "category": { "id": "battle-rifle", "name": "Battle Rifle", "description": "Selective-fire rifles chambered in full-power cartridges" }, "country_of_origin": "US", "year_introduced": 2014, "barrel_length_mm": 406, "weight_empty_g": 4080, "action_type": "gas_operated_direct_impingement"}