| Lacross Enterprises Inc Turning, Laser, Punching, Bending, Welding | Louisville, KY | TurningLaserPunchingBendingWelding | - |
| Lad Engineering LLC Milling, Turning, EDM · ISO 9001, AS9100 | Albuquerque, NM | MillingTurningEDM | ISO 9001, AS9100 |
| Lakota Industries Milling, Turning · AS9100, ITAR | Marysville, WA | MillingTurning | AS9100, ITAR |
| Lamjen Inc Milling, Turning, Welding, Stamping, Casting · ISO 9001 | Erie, PA | MillingTurningWeldingStampingCasting | ISO 9001 |
| Land Sea Air Manufacturing Inc Milling, Turning, Waterjet, Assembly | Westminster, MD | MillingTurningWaterjetAssembly | - |
| Lark Industries Turning, Waterjet, Welding, Assembly · ISO 9001, ISO 13485 | El Paso, TX | TurningWaterjetWeldingAssembly | ISO 9001, ISO 13485 |
| Lawson Precision Machining, Inc Milling, Turning, Welding, Grinding · ISO 9001 | Bucyrus, OH | MillingTurningWeldingGrinding | ISO 9001 |
| Lear Machining & Waterjet Inc Milling, Turning, Waterjet, Welding, Grinding · ISO 9001 | Columbus, IN | MillingTurningWaterjetWeldingGrinding | ISO 9001 |
| Leonard Machine Co, LLC Milling, Turning, Welding · ISO 9001 | Cookeville, TN | MillingTurningWelding | ISO 9001 |
| Liberty Precision Company Milling, Turning, EDM, Grinding, Assembly · ISO 9001 | Houston, TX | MillingTurningEDMGrindingAssembly | ISO 9001 |
| Liberty Precision Manufacturing LLC Milling, Turning, Swiss · ISO 9001, ITAR, CMMC | New Berlin, WI | MillingTurningSwiss | ISO 9001, ITAR, CMMC |
| Liberty Tool Inc Milling, Turning, Welding, Grinding · ISO 9001, AS9100, ITAR | Sterling Heights, MI | MillingTurningWeldingGrinding | ISO 9001, AS9100, ITAR |
| Lindsay Machine Works, Inc Milling, Turning, Laser, Waterjet, Bending, Welding, Grinding | Independence, MO | MillingTurningLaserWaterjetBendingWeldingGrinding | - |
| Linita Design & Mfg. Corp Turning, Welding, Assembly | Lackawanna, NY | TurningWeldingAssembly | - |
| Longleaf Machining LLC Turning, Finishing · ISO 9001, ITAR | Brewton, AL | TurningFinishing | ISO 9001, ITAR |
| Loutech LLC Milling, Turning, Swiss, Finishing · ISO 9001, AS9100, ITAR | Chino, CA | MillingTurningSwissFinishing | ISO 9001, AS9100, ITAR |
| Ltts Machine LLC Milling, Turning · ISO 9001, AS9100, ITAR | Fort Worth, TX | MillingTurning | ISO 9001, AS9100, ITAR |
| LV Swiss Inc Milling, Turning, Swiss, Grinding, Finishing · ISO 9001, AS9100, ITAR, ISO 13485 | La Verkin, UT | MillingTurningSwissGrindingFinishing | ISO 9001, AS9100, ITAR, ISO 13485 |
| M & B Machine, Inc Milling, Turning, Swiss, Welding · ISO 9001, AS9100, CMMC | Carlisle, PA | MillingTurningSwissWelding | ISO 9001, AS9100, CMMC |
| M & S Machining Inc Milling, Turning, Bending, Welding, EDM, Assembly · ISO 9001, AS9100, ITAR | Winchester, KY | MillingTurningBendingWeldingEDMAssembly | ISO 9001, AS9100, ITAR |
| M-Tech Machining LLC Milling, Turning, EDM · ITAR | Edgewood, NM | MillingTurningEDM | ITAR |
| M'kaddesh Group LLC Milling, Turning · AS9100 | Cerritos, CA | MillingTurning | AS9100 |
| M's Machines Milling, Turning, Welding | Monona, IA | MillingTurningWelding | - |
| M&M Machining, Inc Milling, Turning, Welding, Finishing | Ventura, CA | MillingTurningWeldingFinishing | - |
| M2 Performance Solutions LLC Milling, Turning · AS9100, ITAR, CMMC | Cornelius, NC | MillingTurning | AS9100, ITAR, CMMC |
| Mac Machine Company Milling, Turning, Welding, EDM, Grinding · AS9100, ITAR, NADCAP, CMMC | Baltimore, MD | MillingTurningWeldingEDMGrinding | AS9100, ITAR, NADCAP, CMMC |
| Mace Machine LLC Milling, Turning, Swiss, Grinding · AS9100, ITAR, NADCAP | Exeter, NH | MillingTurningSwissGrinding | AS9100, ITAR, NADCAP |
| Machinable Innovations LLC Milling, Turning | Bend, OR | MillingTurning | - |
| Machineworks Manufacturing Milling, Turning, Laser, Bending, Welding, Finishing · ISO 9001, AS9100, ITAR | Northridge, CA | MillingTurningLaserBendingWeldingFinishing | ISO 9001, AS9100, ITAR |
| Machining Tech Milling, Turning, Waterjet, Welding, Stamping, EDM, Grinding | Hazle Township, PA | MillingTurningWaterjetWeldingStampingEDMGrinding | - |
| 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 |
| Malux Machine LLC Milling, Turning, Welding, Grinding | Stratford, CT | MillingTurningWeldingGrinding | - |
| Manutek Mfg LLC Milling, Turning, Waterjet · ITAR | Estacada, OR | MillingTurningWaterjet | ITAR |
| Marinette Machine LLC Turning, Welding, Grinding, Finishing | Marinette, WI | TurningWeldingGrindingFinishing | - |
| Marion Manufacturing Milling, Turning, Welding, Stamping, EDM · AS9100 | West Terre Haute, IN | MillingTurningWeldingStampingEDM | AS9100 |
| Maritech Machine Inc Milling, Turning, Waterjet, Welding, Grinding, Finishing · ISO 9001, AS9100 | Panama City, FL | MillingTurningWaterjetWeldingGrindingFinishing | ISO 9001, AS9100 |
| Mark One Metal Works Turning, Bending, Welding | Sparks, NV | TurningBendingWelding | - |
| Maryland Greater Tool & Manufacturing Milling, Turning, Waterjet, Welding, Grinding, Finishing | Mountain Lake Park, MD | MillingTurningWaterjetWeldingGrindingFinishing | - |
| Maumee Pattern Co Milling, Turning, Casting, EDM · ITAR, CMMC | Toledo, OH | MillingTurningCastingEDM | ITAR, CMMC |
| Max Machine Milling, Turning, Laser, Waterjet, Welding, Grinding, Finishing · ISO 9001 | Elizabethtown, PA | MillingTurningLaserWaterjetWeldingGrindingFinishing | ISO 9001 |
| Maxpol Precision Machining Milling, Turning | Morgan Hill, CA | MillingTurning | - |
| McAllister Tool & Machine Inc Milling, Turning, Swiss · ISO 9001, AS9100, ITAR | Huntsville, AL | MillingTurningSwiss | ISO 9001, AS9100, ITAR |
| McKenzie Machining Inc Milling, Turning, EDM, Grinding · ISO 9001, AS9100, ITAR | San Jose, CA | MillingTurningEDMGrinding | ISO 9001, AS9100, ITAR |
| McNeil Industries Inc Milling, Turning, Welding, Stamping, Grinding, Assembly · ISO 9001, AS9100 | Painesville, OH | MillingTurningWeldingStampingGrindingAssembly | ISO 9001, AS9100 |
| Memac Industries Inc Milling, Turning, Welding, Grinding | Lancaster, OH | MillingTurningWeldingGrinding | - |
| Meridian Industrial Group, LLC Milling, Turning, Welding, Casting · ISO 9001, AS9100 | Holyoke, MA | MillingTurningWeldingCasting | ISO 9001, AS9100 |
| Meridian Manufacturing Inc Milling, Turning, Laser, Welding, EDM, Grinding, Finishing | Ballston Spa, NY | MillingTurningLaserWeldingEDMGrindingFinishing | - |
| Mesatronics Inc Milling, Turning · ISO 9001, AS9100, ITAR, CMMC | Spicewood, TX | MillingTurning | ISO 9001, AS9100, ITAR, CMMC |
| Metal Essence Inc Milling, Turning, Swiss, Finishing, Assembly · ISO 9001, AS9100, ITAR | Longwood, FL | MillingTurningSwissFinishingAssembly | ISO 9001, AS9100, ITAR |