Introduction
This manual provides essential information for the proper use and maintenance of your Williams BM-621 3/8-inch Drive Shallow Socket. Designed for professional and industrial applications, this 21mm, 6-point socket offers reliable performance for fastening and unfastening tasks.
Please read these instructions carefully before use to ensure safe and effective operation and to maximize the lifespan of your tool.
Product Overview and Features
The Williams BM-621 socket is engineered with specific features to enhance its functionality and durability:
- SUPERTORQUE Lobular Openings: Designed to provide greater turning power while minimizing fastener deformation.
- Quick Engagement: Chamfered ends facilitate easy engagement with both 6 and 12-point fasteners.
- Durable Construction: Cold formed from alloy steel, precision machined, and fully heat-treated for strength.
- Easy Maintenance Finish: Features a mirror-like chrome finish that is easy to clean after use.
- Shallow Hex Depth: Allows for easy engagement on short threaded bolts, improving accessibility.

Figure 1: The Williams BM-621 3/8-inch drive shallow socket, 21mm, showcasing its polished chrome finish.

Figure 2: Illustration highlighting the SUPERTORQUE lobular openings, designed for enhanced turning power without damaging fasteners.

Figure 3: Depiction of the socket's construction from cold-formed alloy steel, precision machining, and fully heat-treated process, along with chamfered ends for easy engagement.

Figure 4: Image illustrating the grip rings on the socket, which aid in secure handling and removal, even with oily or gloved hands.
Setup and Installation
- Select the Correct Drive Tool: Ensure you are using a 3/8-inch square drive ratchet, breaker bar, or torque wrench that is compatible with the socket.
- Attach the Socket: Align the square drive opening of the socket with the drive tang of your tool. Push the socket firmly onto the drive tang until it clicks into place, indicating a secure connection.
- Verify Engagement: Gently pull on the socket to confirm it is securely attached to the drive tool before applying force.
Operating Instructions
Follow these steps for safe and effective use of your Williams BM-621 socket:
- Identify Fastener Size: Confirm that the fastener (nut or bolt head) is 21mm. Using an incorrect size socket can damage both the fastener and the socket.
- Position the Socket: Place the socket squarely over the fastener. Ensure full engagement of the socket's 6-point opening with the fastener's head. The chamfered ends are designed to assist with this.
- Apply Force:
- For loosening, apply steady, counter-clockwise force.
- For tightening, apply steady, clockwise force. If a specific torque value is required, use a calibrated torque wrench.
- Maintain Control: Always maintain a firm grip on the drive tool. Avoid sudden jerking motions, which can cause slippage and potential injury or damage.
- Remove Socket: Once the task is complete, pull the socket off the drive tool.

Figure 5: Example of a socket being used with a drive tool to apply force to a fastener.
Maintenance
Proper maintenance ensures the longevity and performance of your Williams socket:
- Cleaning: After each use, wipe the socket clean with a cloth to remove dirt, grease, and debris. The chrome finish is designed for easy cleaning.
- Inspection: Regularly inspect the socket for any signs of wear, cracks, or damage. Pay close attention to the drive opening and the 6-point fastener engagement area.
- Storage: Store the socket in a dry environment to prevent rust. Keep it organized in a tool tray or box to protect it from impacts and loss.
- Lubrication: While the socket itself does not require lubrication, ensure your drive tools are properly maintained and lubricated as per their respective instructions.
Troubleshooting
Most issues with a socket are related to incorrect application or selection:
- Socket Does Not Fit Fastener:
Ensure the fastener is indeed 21mm. If it is, check for any debris or damage on the fastener or inside the socket that might prevent proper seating. Do not force the socket onto an incorrect size fastener.
- Socket Slips on Fastener:
This can occur if the fastener head is rounded or damaged, or if the socket is not fully engaged. Ensure the socket is pushed completely onto the fastener. If the fastener is damaged, consider using a specialized fastener extraction tool.
- Socket Does Not Attach to Drive Tool:
Verify that your drive tool has a 3/8-inch square drive. Check for any obstructions in the socket's drive opening or on the drive tool's tang.
Specifications
Key specifications for the Williams BM-621 3/8 Drive Shallow Socket, 6 Point, 21mm:
| Specification | Detail |
|---|---|
| Model Number | BM-621 (JHWBM-621) |
| Drive Size | 3/8 inch |
| Socket Type | Shallow, 6 Point |
| Size (Metric) | 21mm |
| Material | Chrome Vanadium Steel |
| Finish Type | Polished Chrome |
| Item Weight | 3.2 ounces |
| Product Dimensions | 1.22 x 1.14 x 1.14 inches |
| Measurement System | Metric |
| UPC | 662459212214 |

Figure 6: Detailed dimensional specifications for various Williams 3/8-inch drive shallow 6-point sockets, including the BM-621 model.
Warranty and Support
Williams tools are manufactured to high standards and are designed for durability and performance. For information regarding product warranty, service, or technical support, please refer to the official Williams website or contact their customer service department. Keep your purchase receipt as proof of purchase.
For additional resources and product information, visit the Williams Store on Amazon.





