M-Lok Screw Sizes: Know The Standard For Your Firearm Accessories (2024)

The M-LOK, short for Modular Lock, is a firearm rail interface system developed and patented by Magpul Industries. The M-LOK T-Nut Replacement Set comes with two button-head socket cap screws of the following sizes: 10-24x7/16 and 10-24x3/8. The thread size of the M-LOK Screw Replacement Set is 10#-24X3/8. The M-LOK system is an improvement on the Magpul Original Equipment (MOE) system, which was released in 2008.

M-LOK T-Nut replacement sets

The M-LOK T-Nut Replacement Set is a replacement hardware pack designed for use with all M-LOK accessories. The set typically includes two T-nuts and two pairs of button-head cap screws, one short and one long, to ensure compatibility with various handguard thicknesses.

The screws feature a self-locking reusable thread patch to ensure a secure fit upon installation. The T-nuts and screws are made of 4140 Chromoly Steel with a Mil-Spec Manganese Phosphate finish. The set is manufactured by Magpul Industries and is available on their website, as well as other online retailers such as Amazon and Primary Arms.

Reviews for the Magpul M-LOK T-Nut Replacement Set are generally positive, with customers praising the quality, performance, and ease of installation. Some reviewers mention that the screws are durable and that the M-LOK system is easy to use. The set is also described as a good value, with some customers recommending having extra sets on hand for small parts replacements.

However, there are mixed opinions on the fit of the T-nuts and screws. While some reviewers found that they fit their rails securely, others encountered issues with the screws being too long and making contact with their barrel or the screw heads being too large. It is important to note that generic T-nut and screw sets may not fit M-LOK rails, as the threads are metric and may not be to spec.

In addition to the Magpul set, there are other brands that offer M-LOK T-nut and screw replacement sets, such as Haitengwen, FANGOSS, GOTICAL, and Bontok. These sets vary in terms of the number of T-nuts and screws included, as well as the length of the screws. Some sets also include Allen wrenches or other tools to facilitate installation.

Screw sizes for various handguard accessories

The M-LOK system, short for Modular Lock, is a firearm rail interface system developed and patented by Magpul Industries. The M-LOK T-Nut Replacement Set comes with two button-head socket cap screws of sizes 10-24x7/16" and 10-24x3/8". The screw size is 10 with 24 threads per inch. The M-LOK T-Nut Replacement Set is designed for use with all M-LOK accessories and handguards of various thicknesses.

The M-LOK system offers a slimmer, lighter, and more streamlined handguard/fore-end option compared to the Picatinny rail system. It allows for direct accessory attachment onto the "negative space" (hollow slot) mounting points. The M-LOK rail specification includes metric dimensions and utilizes a T-slot nut capable of only 90-degree rotation.

The thread size for current M-LOK nuts and screws is 10#-24X3/8, but some users may require M3, M4, or M5 nuts. The M-LOK screw size is 0.36" (excluding the Hex Head cap). The M-LOK system typically uses either #8-32 TPI or 10-24 TPI UNC threads, but international variants may use M4 or M5 metric threads instead.

When it comes to screw sizes for various handguard accessories, it's important to ensure compatibility and a secure fit. The M-LOK T-Nut Replacement Set provides two different screw lengths to accommodate different handguard thicknesses. The self-locking reusable thread patch on the screws ensures a tight fit during installation.

Additionally, it's worth noting that the torque specifications for attaching accessories to handguards vary depending on the materials used. For attaching metal accessories to metal handguards, a torque of 4.0 N⋅m (35 lb⋅in) is recommended. When attaching polymer or metal accessories to polymer handguards, or attaching polymer accessories to metal handguards, a lower torque of 1.7 N⋅m (15 lb⋅in) is suggested.

Metric vs imperial screws

M-LOK screws are available in a variety of sizes, and it is important to select the correct size to ensure compatibility with your firearm and accessories. The choice between metric and imperial screws depends on several factors, including personal preference, the target market, and the specific requirements of the application.

Metric and imperial screws differ in their systems of measurement. In the metric system, both the diameter and length of screws are measured in millimetres. On the other hand, imperial screws use inches or fractions of inches to denote these dimensions. For example, an M5 x 80 metric screw is equivalent to a #10 x 2 1/2 imperial screw. This discrepancy can lead to confusion when applying metric bolts to imperial systems and vice versa.

The origin of the screws also plays a role in the choice between metric and imperial. Standard bolts, which use the imperial system, are primarily used in the United States. Metric bolts, on the other hand, are prevalent among international manufacturers. Therefore, American manufacturers intending to sell their products abroad may opt for metric bolts to ensure compatibility with international standards.

The scaling properties of the metric system offer certain advantages over the imperial system. Metric fasteners provide a wider range of sizes within a relatively small range, making it easier to find the perfect fit for specific applications. Additionally, the process of subdividing units of measurement is more straightforward in the metric system. This advantage may be particularly relevant for applications that require precise sizing.

When choosing between metric and imperial screws for M-LOK accessories, it is essential to consider the compatibility, availability, and specific requirements of your firearm and accessories. Both systems have their advantages and limitations, and the ideal choice depends on your unique circ*mstances and preferences.

Screw head types

M-LOK screws are used for attaching accessories to thinner rails. They are available in different head styles and drive styles. The head style of a screw refers to the shape of the screw head, and this can be either countersunk or non-countersunk. Countersunk screw heads are designed to sit flush with the surface of the material, whereas non-countersunk screw heads remain exposed and protrude from the surface.

Cap Head Screws

Cap head screws are characterised by their cylindrical, flat top. They are known for their durability and strength, making them suitable for applications that require high torque and secure fastening. This type of screw head is commonly used in aerospace, automotive, and heavy machinery applications. Cap head screws typically require the use of hex sockets or Torx drives for installation and removal.

Button Head Screws

Button head screws have a round, low-profile top that blends smoothly with surfaces. They offer a balance between strength and aesthetics, making them versatile and widely used. Button head screws are optimised for use with hexagon sockets and Torx drives. They are commonly used in consumer electronics, furniture assembly, and automotive interiors.

Pan Head Screws

Pan head screws feature a rounded top and a flat bearing surface underneath. They sit above the surface of the material, providing a secure fastening and a neat appearance. Pan head screws are versatile and can be used with Phillips, slotted, or Torx drivers. They are commonly used in electronics to secure components within devices.

Countersunk Head Screws

Countersunk head screws have a conical top that allows them to sit flush with or below the surface of the material. This type of screw head is engineered for applications where a smooth surface finish is essential, such as in metal fabrication and aerospace industries. Countersunk head screws are compatible with almost all drive types, including socket, Torx, slotted, and Phillips.

Hexagon Head Bolts

Hexagon head bolts have a six-sided head that provides a robust grasp for tools such as wrenches and spanners. They are commonly used in heavy-duty machinery and are valued for their versatility and reliability. Hexagon head bolts are suitable for a wide range of applications, from industrial to domestic settings.

When choosing the right screw head type for your project, it is important to consider factors such as load-bearing capacity, manufacturability, aesthetic appeal, and security. Each screw head type has its own unique advantages and applications.

Torque specifications

M-LOK, short for Modular Lock, is a firearm rail interface system developed and patented by Magpul Industries. It is a free-of-charge licensed platform that allows for direct accessory attachment onto the "negative space" (hollow slot) mounting points.

The M-LOK system is optimized for both metal and polymer parts. The T-slot nuts have different torque specifications depending on the handguard material:

• Metal accessories to metal handguards: Use a torque of 4.0 N⋅m (35 lb⋅in).
• Polymer or metal accessories to polymer handguards: This requires a torque of 1.7 N⋅m (15 lb⋅in).
• Polymer accessories to metal handguards: Similarly, use a torque of 1.7 N⋅m (15 lb⋅in).

It is important to note that manufacturers may have different torque specifications for their products. Magpul recommends a torque of 25-30 in/lbs for most metal accessories and 15 in/lbs for most polymer accessories.

To ensure proper torque specifications, it is advisable to refer to the specific manufacturer's instructions or seek guidance from a qualified gunsmith.

Frequently asked questions