Part Number
Machine Screw · OEM / vendor part number · NSN 5305-01-167-3291
| Part number | S503 AND S502 |
|---|---|
| Specification family | OEM / vendor part number |
| Item name | Machine Screw |
| Alternate references | PSN 91-556-1-02; 803-135828 PC4,; S503 |
| Unit of issue | EA |
| Cross-referenced NSN | 5305-01-167-3291 |
| Federal Supply Class (FSC) | 5305 — Screws |
| Unit price (USD) | $7.00 |
| Country of origin | Türkiye (Turkey) |
| Lead time | Within 90 days of order |
| Minimum order | May apply — confirm on quote |
| Documentation | Source documentation provided on all orders |
Characteristics decoded from the federal cataloging record for this machine screw. Confirm controlling dimensions against your drawing or standard sheet before ordering.
| Fastener Length | 0.282 Inches Minimum And 0.312 Inches Maximum |
|---|---|
| Head Style | Button |
| Nominal Thread Diameter | 0.500 Inches |
| Screw Material | Copper Alloy 464 Or Steel Comp 302 Or Steel Comp 302B Or Steel Comp 303 Or Steel Comp 303 Plus X Or Steel Comp 303Se Or Steel Comp 303Cu Or Steel Comp 303Ma Or Steel Comp 304 Or Steel Comp 304L |
| Thread Class | 2A |
| Thread Series Designator | Unf |
| Thread Quantity Per Inch | 20 |
Externally threaded fasteners designed to be turned to assemble or adjust parts, including machine screws, cap screws, socket-head cap screws, set screws, self-tapping and thread-forming screws. This is the largest single class in the U.S. supply system and covers a vast range of thread sizes, drive types, head styles, and materials.
Reading the part number. S503 AND S502 is a vendor part number for this machine screw. If your documentation lists a different reference for the same item, include it on the quote and we will confirm the cross-reference.
Price in context. Across the 2,357 items we currently stock in FSC 5305 (Screws), published unit prices run from $0.03 to $14,752.17. At $7.00, this item sits below the class median of $10.52.
Stock activity. This item has appeared once in our supplier stock feed, most recently listed 2026-08-21, with a lot quantity of 1,603 units. Listing activity is a practical signal of ongoing availability; confirm current stock and firm pricing on your quote.
Who orders S503 AND S502. Aircraft owners and MRO shops replacing standard hardware, machine shops and OEMs filling a bill of materials, and government contractors sourcing against NSN 5305-01-167-3291. You can order by part number or by stock number — it is the same item, the same published price, and the same quote form.
Applicable standards. ASME B18.3 / B18.6.3, MIL-DTL / NASM / MS and AN series, ISO metric threads; common materials include carbon and alloy steel, 300/400-series stainless, and A2/A4 stainless per ISO 3506.
Need this part modified, or a similar part made to your print? See our U.S.-based CNC machining services and aerospace machining capability.
Country of origin: Türkiye (Turkey). Turkey is a NATO ally and a normal-trade-relations partner of the United States, and Turkish-origin end items are eligible for a wide range of U.S. federal and DLA procurements.
TAA note: Turkey is not a Trade Agreements Act (TAA) designated country, so these items are generally not eligible for TAA-covered solicitations. They are offerable under the Buy American Act and many non-TAA DLA buys. Buyers are responsible for confirming the origin requirements of their specific solicitation.
Full country-of-origin and source documentation is provided with every order. Fulfillment within 90 days of order. Minimum order may apply.
Items are supplied as stock mil-spec / commercial hardware with source documentation and country-of-origin paperwork on every order. Parts are not supplied with an FAA Form 8130-3 airworthiness tag unless expressly stated on the quote. Buyers installing hardware on certificated aircraft are responsible for acceptance under their own maintenance program, repair station procedures, or owner/operator authority.
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