| Coast Precision Enterprises Milling, Turning · ISO 9001, AS9100, ITAR | San Diego, CA | MillingTurning | ISO 9001, AS9100, ITAR |
| Coastal Machine & Supply Inc Milling, Turning · ISO 9001, AS9100, ITAR, CMMC | Carencro, LA | MillingTurning | ISO 9001, AS9100, ITAR, CMMC |
| Cobalt Enterprises LLC Milling, Finishing · ITAR | Arlington, WA | MillingFinishing | ITAR |
| Colburn Manufacturing Company Milling, Turning · ISO 9001, ISO 13485 | Fridley, MN | MillingTurning | ISO 9001, ISO 13485 |
| Colleen & Herb Enterprises Inc Milling, Turning, Welding | Fremont, CA | MillingTurningWelding | - |
| Collins Custom Manufacturing LLC Milling · ISO 9001, ITAR | Fort Worth, TX | Milling | ISO 9001, ITAR |
| Collins Machine Works Welding, Grinding · CMMC | Portsmouth, VA | WeldingGrinding | CMMC |
| Collins Manufacturing Inc Milling, Turning, EDM · ITAR | Essex, MA | MillingTurningEDM | ITAR |
| Colorado Machine Works, Inc. Milling, Turning | Colorado Springs, CO | MillingTurning | - |
| Columbus Machine Works Milling, Turning, Bending, Welding, EDM, Casting | Columbus, OH | MillingTurningBendingWeldingEDMCasting | - |
| Combs Enterprises Incorporated Milling, Turning, Bending, Welding, Finishing · ITAR | Great Mills, MD | MillingTurningBendingWeldingFinishing | ITAR |
| Comet Fabricating & Welding Co Laser, Bending, Welding | Rockford, IL | LaserBendingWelding | - |
| Commercial Tool & Die Inc Milling, Turning, Welding, Grinding | Marshall, VA | MillingTurningWeldingGrinding | - |
| Compass Machine & Inspection LLC Milling | Houston, TX | Milling | - |
| Compo Engineering LLC Welding, Finishing | Westport, CT | WeldingFinishing | - |
| Component Surfaces Inc Finishing · ISO 9001, ITAR | Poway, CA | Finishing | ISO 9001, ITAR |
| Concise Manufacturing Inc Milling, Turning, Welding, EDM | Salisbury, NC | MillingTurningWeldingEDM | - |
| Connecta Corp Milling, Turning, Swiss | Indianapolis, IN | MillingTurningSwiss | - |
| Connelly Machine WKS Milling, Turning, Waterjet, Welding, Grinding · ISO 9001, ITAR | Santa Ana, CA | MillingTurningWaterjetWeldingGrinding | ISO 9001, ITAR |
| Conner Brothers Machine Co., Inc Milling, Turning, Welding, Grinding · ISO 9001 | Bessemer City, NC | MillingTurningWeldingGrinding | ISO 9001 |
| Conroe Machine, LLC Milling, Turning, Laser, Bending, Welding, EDM, Grinding, Finishing · ISO 9001 | Conroe, TX | MillingTurningLaserBendingWeldingEDMGrindingFinishing | ISO 9001 |
| Consolidated Metal Products Milling, Turning, Bending, Laser, Welding, Stamping · ISO 9001 | Grand Rapids, MI | MillingTurningBendingLaserWeldingStamping | ISO 9001 |
| Container Products Company, LLC Welding | Currie, NC | Welding | - |
| Conti Tool & Die, Inc Milling, Turning, Bending, Welding, Grinding | Akron, OH | MillingTurningBendingWeldingGrinding | - |
| Continental Industries Bending, Laser, Welding | Anaheim, CA | BendingLaserWelding | - |
| Continental Machining Co Milling, Turning, Welding, EDM | Albuquerque, NM | MillingTurningWeldingEDM | - |
| Contract Machining Milling, Turning, Welding · ISO 9001 | Lexington, KY | MillingTurningWelding | ISO 9001 |
| Conturo Prototyping, LLC Milling, Turning | Pittsburgh, PA | MillingTurning | - |
| Copen Machine, Inc Milling, Turning, Swiss, Welding, Grinding · ISO 9001 | Kent, OH | MillingTurningSwissWeldingGrinding | ISO 9001 |
| Coronado Steel Co Turning, Welding, Casting, Metal AM | Youngstown, OH | TurningWeldingCastingMetal AM | - |
| Cortec Precision Sheetmetal Milling, Turning, Bending, Laser, Welding | San Jose, CA | MillingTurningBendingLaserWelding | - |
| Council Stainless & Sheet Metal Bending, Welding, Waterjet | Oklahoma City, OK | BendingWeldingWaterjet | - |
| Coventry Industries LLC Waterjet, Welding, EDM · ITAR | Holly, MI | WaterjetWeldingEDM | ITAR |
| Cox Manufacturing Co Milling, Turning, Swiss, EDM · ISO 9001, ITAR | San Antonio, TX | MillingTurningSwissEDM | ISO 9001, ITAR |
| CP Industries Inc Milling, Welding, Casting | Granger, IN | MillingWeldingCasting | - |
| CPK Manufacturing Milling, Turning, EDM · ISO 9001 | San Jose, CA | MillingTurningEDM | ISO 9001 |
| Crater Industries LLC Milling, Turning, EDM, Grinding, Assembly | Santa Clarita, CA | MillingTurningEDMGrindingAssembly | - |
| Creative Machining Solutions Welding, Finishing | Walford, IA | WeldingFinishing | - |
| Creative Machining Systems Inc Milling, Turning, Welding, EDM, Grinding, Finishing | Trenton, NJ | MillingTurningWeldingEDMGrindingFinishing | - |
| Criterion Manufacturing Turning, Welding | Waterloo, IA | TurningWelding | - |
| Criterion Precision Machining Milling, Turning · ISO 9001, AS9100 | Cleveland, OH | MillingTurning | ISO 9001, AS9100 |
| Critical Defense Inc Milling, Turning, Bending, Welding, Grinding, Assembly | Windber, PA | MillingTurningBendingWeldingGrindingAssembly | - |
| Crowdynamics LLC Milling, Turning, Finishing, Assembly | Albuquerque, NM | MillingTurningFinishingAssembly | - |
| Crown Fabricators Welding | Las Vegas, NV | Welding | - |
| Crown Machine Inc Milling, Turning, Welding, EDM · ISO 9001 | Rockford, IL | MillingTurningWeldingEDM | ISO 9001 |
| Crucial Component Machining LLC Milling, Turning, Swiss, EDM | Concord, NH | MillingTurningSwissEDM | - |
| CS Precision Manufacturing Inc Turning, Bending, EDM, Finishing · ISO 9001 | Gering, NE | TurningBendingEDMFinishing | ISO 9001 |
| CTC Machining, LLC Milling, Turning | Hampstead, MD | MillingTurning | - |
| Cte Machine Inc Milling, Turning, Finishing | Groveland, FL | MillingTurningFinishing | - |
| Cubitek, Inc Milling, Turning, EDM, Grinding · ISO 9001, AS9100 | Brentwood, NY | MillingTurningEDMGrinding | ISO 9001, AS9100 |