| IronStrong Metal Fabrication LLC Milling, Bending, Laser, Welding | Lancaster, PA | MillingBendingLaserWelding | - |
| Jaffa Precision Engineering Inc Milling, Turning, Swiss, Welding, Grinding, Finishing · ISO 9001 | Riverside, CA | MillingTurningSwissWeldingGrindingFinishing | ISO 9001 |
| Jetfab LLC Milling, Turning, Laser, Waterjet, Punching, Bending, Welding | Lowell, MA | MillingTurningLaserWaterjetPunchingBendingWelding | - |
| JMC Acquisition LLC Milling, Turning, Swiss, Welding · ISO 9001, AS9100, ISO 13485 | Sanford, NC | MillingTurningSwissWelding | ISO 9001, AS9100, ISO 13485 |
| JMS Machine, Inc Milling, Turning, EDM, Grinding | Columbia City, IN | MillingTurningEDMGrinding | - |
| Johnson Manufacturing Milling, Turning, Grinding · AS9100 | Huntington Beach, CA | MillingTurningGrinding | AS9100 |
| Jrev Enterprises LLC Milling, Turning, Waterjet · ITAR | Espanola, NM | MillingTurningWaterjet | ITAR |
| JRS Precision Machine & Design LLC Milling, Turning | Lakeville, MA | MillingTurning | - |
| JV Precision Machine Co Milling, EDM · ISO 9001, AS9100, ITAR | Seymour, CT | MillingEDM | ISO 9001, AS9100, ITAR |
| Kam Tool & Die Milling, Turning, EDM, Grinding · ISO 9001 | Zebulon, NC | MillingTurningEDMGrinding | ISO 9001 |
| Kennebec Technologies Milling, Grinding, Assembly | Augusta, ME | MillingGrindingAssembly | - |
| Kennley Corp Milling, Turning, Grinding, Finishing | North Chesterfield, VA | MillingTurningGrindingFinishing | - |
| Kent Machine Milling, EDM, Grinding | Indianapolis, IN | MillingEDMGrinding | - |
| Kinetik Systems LLC Milling, Turning, Welding | Tucson, AZ | MillingTurningWelding | - |
| Kinross Fab & Machine Inc Milling, Turning, Laser, Welding, Grinding, Finishing | Kincheloe, MI | MillingTurningLaserWeldingGrindingFinishing | - |
| Kinship Precision LLC Milling, Turning, Swiss, Laser · ISO 9001, ISO 13485 | Melbourne, FL | MillingTurningSwissLaser | ISO 9001, ISO 13485 |
| Kiski Precision Industries, LLC Milling, Turning, Welding, Assembly | Leechburg, PA | MillingTurningWeldingAssembly | - |
| KP Manufacturing Milling, Casting, Finishing, Assembly | Spencer, IA | MillingCastingFinishingAssembly | - |
| Krametech, Inc Milling, Finishing, Assembly | Lake Zurich, IL | MillingFinishingAssembly | - |
| Krukemeier Machine Milling, Turning, EDM · AS9100, NADCAP | Indianapolis, IN | MillingTurningEDM | AS9100, NADCAP |
| Kyron Tool & Machine Co., Inc Milling, Turning, Welding | Columbus, OH | MillingTurningWelding | - |
| L.F. Industries, Inc Milling · ISO 9001, AS9100 | Carlsbad, CA | Milling | ISO 9001, AS9100 |
| Lakes Area Manufacturing Co Milling, Grinding | Shafer, MN | MillingGrinding | - |
| Leanwerks, LLC Milling, Turning, Welding, Casting, Grinding, Assembly · ISO 9001, AS9100, ITAR, CMMC | Ogden, UT | MillingTurningWeldingCastingGrindingAssembly | ISO 9001, AS9100, ITAR, CMMC |
| Lee Precision Machine Shop Inc. Milling, Turning, Bending, Welding, EDM · ISO 9001, ITAR | Athens, AL | MillingTurningBendingWeldingEDM | ISO 9001, ITAR |
| Liberty Precision Company Milling, Turning, EDM, Grinding, Assembly · ISO 9001 | Houston, TX | MillingTurningEDMGrindingAssembly | ISO 9001 |
| Logan Machine Co Milling, Turning, Bending, Welding | Akron, OH | MillingTurningBendingWelding | - |
| Long Machine Milling, Turning, Grinding | Temecula, CA | MillingTurningGrinding | - |
| Loper Machine LLC Milling, Turning | Edgewood, MD | MillingTurning | - |
| LP Precision, Inc Milling, Turning, Grinding, Finishing | Santa Clara, CA | MillingTurningGrindingFinishing | - |
| Luso Machine NJ, LLC Milling, Turning, Welding, EDM · ISO 9001 | Newark, NJ | MillingTurningWeldingEDM | ISO 9001 |
| M & M Sheet Metal, Inc Milling, Laser, Bending, Welding, Forging · ISO 9001, ITAR, CMMC | Williamsport, PA | MillingLaserBendingWeldingForging | ISO 9001, ITAR, CMMC |
| M W M Services, Inc Milling, Welding, EDM | Riviera Beach, FL | MillingWeldingEDM | - |
| M-Tech Machining LLC Milling, Turning, EDM · ITAR | Edgewood, NM | MillingTurningEDM | ITAR |
| Mac Smith Corp Milling, Turning, Laser, Waterjet, Bending, Welding, Stamping, Grinding | Gardena, CA | MillingTurningLaserWaterjetBendingWeldingStampingGrinding | - |
| Machine Craft Northwest Inc Milling, Turning, Welding | Lebanon, OR | MillingTurningWelding | - |
| Machine Tech Inc Milling, Turning, EDM · ISO 9001 | Houma, LA | MillingTurningEDM | ISO 9001 |
| Machine Time Inc Milling, Turning, Bending, Welding · ISO 9001, AS9100 | Nicholasville, KY | MillingTurningBendingWelding | ISO 9001, AS9100 |
| Machinewell, Inc Milling, Welding · ISO 9001 | Grygla, MN | MillingWelding | ISO 9001 |
| Machinist Group Corporation Milling, Turning, Waterjet · ISO 9001, ITAR | Reno, NV | MillingTurningWaterjet | ISO 9001, ITAR |
| Magna Tool Inc Milling, Turning, Welding · AS9100 | Cypress, CA | MillingTurningWelding | AS9100 |
| Magnetic Inspection Laboratory, Inc Milling, Welding, Finishing · ISO 9001, AS9100, NADCAP, ISO 13485 | Elk Grove Village, IL | MillingWeldingFinishing | ISO 9001, AS9100, NADCAP, ISO 13485 |
| Malux Machine LLC Milling, Turning, Welding, Grinding | Stratford, CT | MillingTurningWeldingGrinding | - |
| Manufacturing Standard, LLC Milling, Turning, Swiss, Stamping, Casting · ISO 9001, AS9100, IATF 16949 | Poway, CA | MillingTurningSwissStampingCasting | ISO 9001, AS9100, IATF 16949 |
| Marcu Manufacturing of Georgia, LLC Milling, Turning, Stamping · ISO 9001 | Buford, GA | MillingTurningStamping | ISO 9001 |
| Marton Precision MF Milling, Turning, Waterjet, Welding, EDM, Finishing · ISO 9001, AS9100, ITAR | Fullerton, CA | MillingTurningWaterjetWeldingEDMFinishing | ISO 9001, AS9100, ITAR |
| Masters Machine Company Milling, Turning, Swiss, Grinding, Finishing · ISO 9001, ITAR | Bristol, ME | MillingTurningSwissGrindingFinishing | ISO 9001, ITAR |
| Matrix Metalworks LLC Milling, Welding · ISO 9001 | Sugar Land, TX | MillingWelding | ISO 9001 |
| Max Machining LLC Milling, Turning, Laser, Bending · ITAR, CMMC | Telford, PA | MillingTurningLaserBending | ITAR, CMMC |
| MaxFab Milling, Laser, Punching, Bending, Welding, Stamping, Finishing, Assembly | Madison, AL | MillingLaserPunchingBendingWeldingStampingFinishingAssembly | - |