| Mountain Defense LLC Milling, Turning, EDM, Assembly | Mentor, OH | MillingTurningEDMAssembly | - |
| Mountain Machine Works Milling, Turning, Welding · ISO 9001, ITAR | Auburn, ME | MillingTurningWelding | ISO 9001, ITAR |
| Mountain Precision Tool Co, Inc Milling, Turning, Laser, Waterjet, Punching, Bending, Welding, EDM, Grinding, Finishing | Blacksburg, VA | MillingTurningLaserWaterjetPunchingBendingWeldingEDMGrindingFinishing | - |
| Mountain Valley Machine, Inc Milling, Turning, Waterjet, Bending, Welding, EDM, Grinding · ISO 9001 | Smithfield, UT | MillingTurningWaterjetBendingWeldingEDMGrinding | ISO 9001 |
| Mountain View Machine and Welding Milling, Turning, Waterjet, Welding, EDM | Logan, UT | MillingTurningWaterjetWeldingEDM | - |
| MRC Machine Inc Milling, Turning, Welding | Pound, WI | MillingTurningWelding | - |
| MSP Maufacturing Milling, Turning, Bending, Welding, Finishing, Assembly | Bloomington, IN | MillingTurningBendingWeldingFinishingAssembly | - |
| Mueller Machining LLC Milling, Turning, Laser, Bending, Grinding, Finishing | Salem, OR | MillingTurningLaserBendingGrindingFinishing | - |
| Multi Machining Capabilities, Inc. Milling, Turning, EDM | Romulus, MI | MillingTurningEDM | - |
| Multi-Machining Co Inc Milling, Turning, Finishing, Assembly | Greenville, TX | MillingTurningFinishingAssembly | - |
| Multiplex Machining Milling, Turning · AS9100 | Houston, TX | MillingTurning | AS9100 |
| Murphy Machine Products, Inc Milling, Turning, Swiss, Grinding, Finishing · ISO 9001 | Wood Dale, IL | MillingTurningSwissGrindingFinishing | ISO 9001 |
| MVN Machining LLC Milling, Turning | Santa Clara, CA | MillingTurning | - |
| O&R Precision Milling, Turning, Swiss, Stamping, EDM, Grinding · ISO 9001 | Berne, IN | MillingTurningSwissStampingEDMGrinding | ISO 9001 |
| Octal Corporation Milling, Turning, Welding, Grinding, Assembly · ISO 9001, AS9100 | Teaneck, NJ | MillingTurningWeldingGrindingAssembly | ISO 9001, AS9100 |
| Odat Machine Milling, Turning, Welding, Grinding | Gorham, ME | MillingTurningWeldingGrinding | - |
| OGS Industries Turning, Bending, Laser, Welding, Stamping · ISO 9001, AS9100, ITAR, IATF 16949 | Akron, OH | TurningBendingLaserWeldingStamping | ISO 9001, AS9100, ITAR, IATF 16949 |
| Olson Custom Designs LLC Milling, Turning, Bending, Welding · ISO 9001, ITAR, ISO 13485 | Indianapolis, IN | MillingTurningBendingWelding | ISO 9001, ITAR, ISO 13485 |
| Olympus Machining Milling, Turning · ITAR, CMMC | Hanover, PA | MillingTurning | ITAR, CMMC |
| Omega Precision Milling, Turning · ISO 9001 | Santa Fe Springs, CA | MillingTurning | ISO 9001 |
| Omikron Engineering, Inc Milling, Turning, Swiss, Assembly · ISO 9001 | Chatsworth, CA | MillingTurningSwissAssembly | ISO 9001 |
| Omni Machine Works Inc Milling, Turning, Welding, EDM, Grinding | Covington, GA | MillingTurningWeldingEDMGrinding | - |
| Omni Precision Components Milling, Turning, Finishing · ISO 9001 | Holland, MI | MillingTurningFinishing | ISO 9001 |
| OMS Precision Machining Milling, Turning, Swiss, Casting, Grinding, Finishing · ISO 9001, ITAR | Oshkosh, WI | MillingTurningSwissCastingGrindingFinishing | ISO 9001, ITAR |
| On Sh0re USA LLC Milling, Turning | Glendale Heights, IL | MillingTurning | - |
| Onamac Industries, Inc Milling, Turning, Casting, Grinding · ISO 9001, AS9100 | Everett, WA | MillingTurningCastingGrinding | ISO 9001, AS9100 |
| Onium Machine and Fabrication, LLC Milling, Turning, Laser, Bending, Welding, Assembly · ISO 9001 | Winder, GA | MillingTurningLaserBendingWeldingAssembly | ISO 9001 |
| Onodi Tool & Engineering Co Milling, Turning, Welding, Assembly · ISO 9001 | Melvindale, MI | MillingTurningWeldingAssembly | ISO 9001 |
| Operateup Inc Milling, Turning, Punching, Welding, Stamping · ISO 9001 | Orange, MA | MillingTurningPunchingWeldingStamping | ISO 9001 |
| Owens Industries, Inc. Milling, Turning, Welding, EDM, Casting, Metal AM · ISO 9001, AS9100 | Oak Creek, WI | MillingTurningWeldingEDMCastingMetal AM | ISO 9001, AS9100 |
| P & N Machine Co, Inc Milling, Turning, Swiss, Laser, Welding, EDM, Finishing · ISO 9001, ITAR, ISO 13485 | Houston, TX | MillingTurningSwissLaserWeldingEDMFinishing | ISO 9001, ITAR, ISO 13485 |
| P3D Creations LLC Milling, Turning, Welding, EDM, Grinding, Finishing · ITAR, CMMC | Maitland, FL | MillingTurningWeldingEDMGrindingFinishing | ITAR, CMMC |
| Pace Machine & Tool, Inc Milling, Turning, Grinding · ISO 9001, AS9100, ITAR | Stuart, FL | MillingTurningGrinding | ISO 9001, AS9100, ITAR |
| Pacon Mfg, Inc Milling, Turning, Welding, Finishing · ISO 9001 | Livermore, CA | MillingTurningWeldingFinishing | ISO 9001 |
| Padgett Machine Tools Co Inc Milling, Turning, Stamping, Finishing · AS9100 | Gatesville, TX | MillingTurningStampingFinishing | AS9100 |
| Painter Tool Incorporated Milling, Turning, Welding, EDM | Irwin, PA | MillingTurningWeldingEDM | - |
| Palmer Precision Milling, Turning | Tucson, AZ | MillingTurning | - |
| Panther Precision Machine Inc Milling, Turning, Welding | Anoka, MN | MillingTurningWelding | - |
| Paradigm Industrial Milling, Turning, Waterjet, Bending, Welding, EDM, Grinding, Assembly · ISO 9001, ITAR, CMMC | Dayton, OH | MillingTurningWaterjetBendingWeldingEDMGrindingAssembly | ISO 9001, ITAR, CMMC |
| Paradorn, LLC Milling, Turning · ITAR | White Plains, MD | MillingTurning | ITAR |
| Paramount Machine Milling, Turning, EDM · ISO 9001, AS9100, ITAR | Salt Lake City, UT | MillingTurningEDM | ISO 9001, AS9100, ITAR |
| Park Precision Machining Inc Milling, Turning | Minneapolis, MN | MillingTurning | - |
| Pathway Precision Manufacturing LLC Milling, Turning, Swiss, Laser, Welding, EDM, Grinding, Finishing · ITAR, ISO 13485, CMMC | Memphis, TN | MillingTurningSwissLaserWeldingEDMGrindingFinishing | ITAR, ISO 13485, CMMC |
| Patience Metal Fab Turning, Bending, Welding | Brooklyn Center, MN | TurningBendingWelding | - |
| Patriot Manufacturing LLC Milling, Turning · ISO 9001 | Plymouth, MI | MillingTurning | ISO 9001 |
| PDQ Machine Shop, Inc Milling, Turning · ISO 9001 | Houston, TX | MillingTurning | ISO 9001 |
| Peerless Precision Inc Milling, Turning, Welding, Grinding · ISO 9001, AS9100, ITAR | Westfield, MA | MillingTurningWeldingGrinding | ISO 9001, AS9100, ITAR |
| Pegasus Machining Solutions Milling, Turning, Finishing | San Jose, CA | MillingTurningFinishing | - |
| Pegasus Mfg Inc Milling, Turning, Metal AM · ISO 9001, AS9100 | Galesburg, IL | MillingTurningMetal AM | ISO 9001, AS9100 |
| Pemco-Naval Engineering Works Inc Turning, Waterjet, Welding | Pascagoula, MS | TurningWaterjetWelding | - |