Precision Shoulder Screws 101: What You Need to Know

Versatility. Precision. A wide range of manufacturers;  A broad range of uses.

In the world of fasteners, precision shoulder screws are classified as Electronic Hardware.  Unlike their cousin, the Shoulder Bolt aka Stripper Bolt, they are not governed by Industrial Fastener Institute, ASME, or ANSI standards.  Instead, precision shoulder screws’ specifications are at the manufacturer’s discretion. They are widely used in assemblies across many industries, including automotive to aerospace. This Buyer’s Guide is intended to empower buyers with the information needed to efficiently purchase precision shoulder screws. In this Buyer’s Guide, we’ll take a closer look at OEM brands and functional equivalents to brand-name precision shoulder screws.  This will include a list of manufacturers, a link to our cross-reference tables, popular materials and sizes available off the shelf, and mil-spec options with certifications.  Read on to learn more about precision shoulder screws.

Precision Shoulder Screws 101: What You Need to Know

Let’s kick things off by reviewing just what precision shoulder screws are. These screws are fasteners with an unthreaded cylindrical shoulder located between the thread and the screwhead. The “shoulder” section is generally wider in diameter than the threaded section of the screw, thereby providing a small axis area where certain moving parts can effectively operate.  

As highlighted above, Precision shoulder screws consist of just three main parts, These parts are:

  • The unthreaded shoulder
  • The threaded portion
  • The head

These three parts inform the description or name of the part.  Specifically, these screws are named based on the shoulder diameter, the shoulder length and the threaded portion diameter, and thread length. For example, a popular shoulder screw is a 3/16 shoulder diameter x 1” long x 8-32 thread in SS18-8 with a hex-socket drive.  This fastener is manufactured by at least even OEM fastener brand.  

Popular markets where precision shoulder screws are utilized include:

  • Aerospace
  • Automotive
  • Hydraulics and electronics
  • Instruments
  • Miscellaneous machinery
  • Military
  • Any assembly where moving parts rotate

In the next section, we’ll get into materials and sizes.

Materials and Sizes

Off-the-shelf “stock” Precision shoulder screws are available in a range of diameters, typically from 1/8″ to 1/2″ shoulder diameter inch and M4 to M14 diameter metric.  The tolerance range is extremely precise with these Precision components. In fact, the diameter tolerance is typically +.000/-.0001 to +.0005/-.0015.

Here’s some other information about precision shoulder screws:

  • Standard stock materials include Stainless Steel 300 series (aka 18-8) and 416 stainless steel.
  • Screws can be manufactured in 316 stainless steel and other special alloys, but typically involve a longer lead time.
  • Custom diameters and lengths are also offered by many manufacturers, but also often involve a longer lead time.

How to Order

The easiest way to order precision shoulder screws is by OEM part number. If you don’t know the part number or don’t have a part number, then you’ll need to provide the description and specifications required as per the previous example. Specifications necessary to name and order the correct precision shoulder screw include:

  • Shoulder diameter
  • Shoulder length
  • Thread size
  • Material and finish

Additionally, you’ll need to determine whether you want a hex socket or a slotted drive. Phillips, Torx, and other drives may also be offered, but typically only in certain screw sizes and materials and may not be available off the shelf. 

Other Screw Considerations

As we noted above, precision shoulder screws are used in a wide range of end-use applications and are made by a variety of fastener OEMs. Amatom, Cambion, Concord, Globe, HH Smith, Keystone, Lyn-tron, Misumi, Pic Design, RAF, and WM Berg are the main OEM brands offering precision shoulder screws in the marketplace.  A comprehensive selection of Precision Shoulder Screws is also offered by McMaster-Carr (tight tolerance series), MSC, and Grainger. You can also find Precision Shoulder Screws under their Mil-Spec numbers, which include MS51575 and MS51576, and are available DFARS-compliant with full paperwork.


Crossing your brand part number to a generic equivalent is one strategy to improve your supply chain efficiency, reduce long lead times and save money.  MF Supply maintains a cross-reference list where you can check to see if the OEM part number and product description specified in your design has a generic alternative.  If it does, it is likely that you can employ a functional equivalent strategy in your purchasing department to streamline efficiency, resulting in reduced lead times and financial savings, while maintaining quality. 

MF Supply can help you cross reference your part to determine your options. 

Certifications and COC

If you require an American Made or DFARs shoulder screw, you may want to convert your OEM brand precision shoulder screw to a Mil-spec MS51575 and MS51576.  If your customer requires one, full certification and test reports are available for American-made and Mil-Spec parts for an additional fee. Contact your manufacturer today to learn more about COCs and other certifications that may be required based on your needs and the needs of your customers.

Contact MF Supply for Precision Shoulder Screws

If you’re looking for a reliable, high-quality manufacturer of precision shoulder screws, partner with MF Supply today. With a full range of commercial and Mil-Spec parts, brand names and generic equivalents, and custom offerings, we’re committed to finding the right screw for your application to help serve as a true extension of your purchasing department.  With more than 50 years of experience, we help manufacturers with supply chain efficiency, including shortening lead times,  getting the most competitive pricing, multi-sourcing parts, and preventing supply chain disruptions currently plaguing manufacturers.

In addition to our stock options, we also offer parts that are DFARS and ROHS compliant, can create parts in exotic materials and custom finishes, and are committed to creatively solving any problems that you may be facing through innovative sourcing practices.

We also offer special services and solutions that include same-day drop ship direct straight from the factory, custom sizes, custom material and plating options, DFARS parts with COC, and more.

For more information on how MF Supply can help act as a true extension of your purchasing and planning department, visit our website, visit our blog or contact us today to learn more. We’re standing by and ready to help you find the right screw.

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