What Size Scope Base Screw Fits Most?

When mounting a scope base, the most common screw thread size is 6-48. This is a special thread size, differing from the more common 6-32 and 6-40 pitch. The 6-48 screw has a diameter of .138 inches, with 48 threads per inch. The drill size for a 6-48 screw is a #32. While less common, some scope bases use #8-40 screws, which are larger and stronger.

#6-48 is the most common thread size

The first number refers to the size of the screw, in this case, a #6 screw. The second number indicates the number of threads per inch, so for #6-48, there are 48 threads per inch. The diameter of a #6 screw is approximately .138 inches, and the corresponding tap drill for a 6-48 screw is a #32 drill.

It is important to note that while #6-48 is the most common thread size, there are also scope base screws with #8-40 threads. The #8-40 screws are larger and, therefore, stronger than the #6-48 screws. Remington, for instance, has started offering rifles drilled and tapped for #8 screws, which have a diameter of approximately .165 inches.

When working with scope base screws, it is crucial to use the correct thread size and type to ensure a secure and proper fit for your firearm.

#8-40 is a stronger alternative

When it comes to scope base screws, #8-40 is a stronger alternative to the more common #6-48 screws. The number refers to the diameter of the screw, with #8 being larger than #6, and the second number denotes the number of threads per inch.

#8-40 screws are a good option for heavier-calibre rifles as they provide more strength and stability. They are often used for larger rifles that require more robust screws, such as the Remington 700 and Savage 112 in 338 Lapua Mag. If you have a rifle that requires more holding power, #8-40 screws can be a good choice.

However, it's important to note that #8-40 screws won't fit through holes drilled for #6-48 screws. If you're considering switching to #8-40 screws, you'll need to ensure your scope base has the correct hole size or have a competent gunsmith retap your receiver.

#8-40 screws are available in various finishes, including black oxide and stainless steel, and can be found at various retailers, including Amazon and Brownells. They are also offered in different head styles, such as fillister, oval, and flat, allowing for a customised look and feel for your rifle.

By choosing #8-40 screws, you gain the advantage of increased strength and durability, making them a reliable choice for your rifle's scope base.

#6-48 uses a #32 tap drill

When it comes to scope mounts and rings, torque is crucial. It is essentially a measure of the twist around an axis and the force associated with it. If the screws are too loose, your scope will shift with the recoil of the rifle, and if they are too tight, they can damage your scope or become difficult to remove.

To ensure the screws are just right, it is important to use the correct tap drill size. For a #6-48 screw, a #32 tap drill is the appropriate size. This specific screw size is commonly used in scope base screws, which secure the scope base to the rifle.

By using the correct tap drill size, you can create the right amount of torque when tightening the screws. This will help prevent the scope from moving due to recoil or vibration. It is also important to follow the manufacturer's torque specifications for scope rings, as they can vary depending on the scope model.

In addition to using the correct tap drill size, it is recommended to use a torque wrench to tighten the screws. This tool allows you to apply the precise amount of torque specified by the manufacturer, reducing the risk of over-tightening or under-tightening the screws.

Remember, scope mounts and rings play a crucial role in maintaining the accuracy and precision of your rifle scope. Taking the time to use the correct tools and follow the manufacturer's specifications will ensure a secure and accurate setup for your firearm.

#8-40 is .026 larger in diameter than #6-48

When it comes to scope base screws, it's essential to understand the specifics of screw sizes to ensure a secure and precise fit. The most common sizes for scope base screws are #6-48 and #8-40, and it's important to know the differences between these two sizes.

The #8-40 screw size is characterised by its diameter, which is 0.026 inches larger than the #6-48 screw. This may seem like a minute difference, but it is significant when it comes to ensuring a proper fit. The larger diameter of the #8-40 screw provides increased strength and stability, making it a preferred choice for applications that require a more robust and secure connection.

The #6-48 screw, on the other hand, has a slightly smaller diameter. This smaller size can be advantageous in situations where space is limited or when working with smaller components. The #6-48 screw is commonly used in applications where a more compact and lightweight setup is prioritised.

It's worth noting that the number before the dash in the screw size designation indicates the screw's diameter, with larger numbers corresponding to larger diameters. In this case, the "8" in #8-40 indicates a larger diameter than the "6" in #6-48. This standard sizing convention helps ensure that users can select the appropriate screw size for their specific application.

When choosing between #8-40 and #6-48 scope base screws, it's important to consider the trade-offs between size and strength. The #8-40 screw offers increased diameter and strength, making it ideal for applications requiring a sturdy and secure connection. On the other hand, the #6-48 screw's slightly smaller diameter can be beneficial in space-constrained situations or when working with smaller or lightweight components. Ultimately, the choice between these two common screw sizes depends on the specific requirements of your scope setup.

#8-40 is used for Remington 6R rifles

#8-40 screws are a less common size for scope base screws, with most receivers being 6-48. The number refers to the size of the screw, with the number getting smaller as the diameter decreases. Therefore, a #6 screw is smaller than a #8 screw. The second number refers to the number of threads per inch, so 40 threads per inch in this case.

#8-40 screws are a bump in fastener diameter compared to the more common #6-48 screws. If you have a rifle that requires #8-40 screws, such as the Remington 6R, you will need to ensure that you purchase a scope base with holes drilled out wide enough to accommodate the larger screw size.

Some rifles that use #8-40 screws include the Remington 700 in 338LM and the Savage 112 in 338 Lapua Mag. If you are using a heavier calibre rifle, it is recommended to use #8-40 screws as they provide a more secure fit.

It is important to check the screw size required for your rifle before purchasing a scope base, as using the wrong size screws can damage your rifle. If you are unsure, it is best to consult a gunsmith or a rifle expert to ensure you are using the correct size screws for your rifle.

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