- Canik
- CCI
- Century Arms
- Champion Traps & Targets
- Chaos Gear Supply
- Charles Daly
- Charter Arms
- Chiappa Firearms
- Chip McCormick "CMC"
- Christensen Arms
- Cimarron
- Citadel
- Cloud Defensive
- CMC Products
- CMC Triggers
- CMMG
- Cold Steel
- Cole-TAC
- Colt's Manufacturing
- Columbia River Knife & Tool "CRKT"
- CompMag
- CorBon
- Crimson Trace Corporation
- Crosman
- Cross Armory
- Cross Industries
- Crucial Concealment
- CVA
- CZ
- D-Lead
- DAC
- Daisy
- Dan Wesson
- Daniel Defense
- DDT
- Dead Air Armament
- Derya
- DeSantis Gunhide
- diamondback barrels
- Diamondback Firearms
- Die Free Co
- Discreet Carry Concepts
- DNZ
- Don Hume
- Doublestar Corp.
- DoubleTap
- DPMS
- DS Arms
- DuraMag
- Eagle Industries