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Savage Rifle Screw Size Guide: How to Identify #6-48 vs #8-40

Recently, Savage made a change to the screw size used in some of their rifles. Starting sometime in 2020, instead of using the traditional #6-48 screws, they began using #8-40 screws in certain models. This change may cause confusion among users who may not be aware of the different screw sizes.

It is important to note that the change in screw size is not a simple matter of replacing the screws. According to information from leading manufacturers of scope mounts for the Savage Model 110, it is necessary to purchase an appropriate scope mount for the specific screw size. Users must ensure that the scope mount they purchase is compatible with the screw size of their rifle to ensure proper fit and function.

There are a couple of ways you can check the screw size on your rifle before purchasing a scope mount.

Option 1: Do the Hex Key Fit Test

The first thing you could do to see if your Savage Model 110 came with #6-48 or #8-40 screws is to do a so-called “hex key fit test”.

Insert a 1/8” hex wrench into the screw holes on the receiver. If the hex key fits snugly into the holes, it indicates that the screw hole size is 8-40. If it does not fit at all, it means the screw hole size is 6-48.

A 1/8" Hex Key
A 1/8″ Hex Key (Source: OTC Brand)

Option 2: Try Measuring the Screws

Another way is to measure the screws with a pair of calipers. This option comes in handy if you already have the screws that fit, but you aren’t sure what size are they.

To do this, you will need a pair of calipers. If the screws measure approximately 3.5 mm (0.138 inches), it indicates that the screw hole size is 6-48. If the screws measure approximately 4.17 mm (0.164 inches), it indicates that the screw hole size is 8-40.

Keep in mind that these measurements are approximate, but you should be able to roughly determine the screw size.

Calipers (Source: Wikipedia)

Option 3: Search for #8-40 Identifier

Savage centerfire rifles manufactured in 2021 or later that have receivers with #8-40 screw holes will have an identifier to help distinguish them from older models.

Savage Model 110 Screw Size

Specifically, Model 110s with #8-40 screw holes will have an identifier on the bolt handle slot, as depicted in the image below.

This identifier will be located on the top of the receiver and will be clearly visible when looking at the rifle from the side.

Savage Model 110 8-40 screws identifier
Savage Model 110 #8-40 Screw Size Identifier (Source: Savage Arms)

Savage Axis Screw Size

AXIS models, on the other hand, are a tad more complicated in this regard.

Savage Axis models made before 2021 have flat cuts along the top of the receiver, as depicted in the image.

Newer models with #8-40 screw holes, however, will not have these flat cuts.

Instead, the Axis receiver drilled for the #8-40 screws will appear completely round when viewed from the rear or back of the receiver.

6-48 vs 8-40 screws on savage axis
Savage Axis #8-40 Screw Size Identifier (Source: Savage Arms)

Another thing that can help you identify a newer Axis model with 8-40 screws is the serial number. Savage Axis Rifles with serial numbers higher than N936371 are drilled and tapped for #8-40 screws.

Option 4: List of Savage Models with #8-40 Screws

Savage provides a list of models that supposedly come drilled for 8-40 screws, but they go on and call this list “not all-inclusive”. This is why we don’t recommend you rely entirely on this list.

Models with #8-40 screw holes on the Savage’s list are:

  • 110 Ultralite
  • 110 Ultralite Camo
  • 110 Elite Precision
  • 110 Elite Precision Left Hand
  • 110 Precision
  • 110 Precision Left Hand
  • AXIS II Precision
  • 110 Scout
  • 110 Wolverine/110 Haymaker
  • 10 GRS
  • 110 Tactical
  • 110 Tactical Left Hand
  • 110 Tactical Desert
  • 110 Tactical Desert Left Hand
  • 110 Timberline
  • 110 Timberline Left Hand
  • 10/110 BA Stealth
  • 10/110 Stealth Evolution
  • 450 Bushmaster caliber models
  • 338 Lapua caliber models

Ask for Help with Savage Scope Mounts

If you need additional help finding a scope mount with the correct screw size for your Savage rifle, you can contact us at [email protected]. One of our salespeople will readily assist you.

Savage Rifle Screw Size Guide: How to Identify #6-48 vs #8-40
Article Name
Savage Rifle Screw Size Guide: How to Identify #6-48 vs #8-40
"To mount scope mounts on Savage rifles, you need to determine if they are drilled for #6-48 or #8-40 screws."
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Optics Trade
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  • Savage model 110
    High country 6.5 prc
    Accufit & Accutrigger

    I’m having problems finding pictnanny rail scope bases and screws. I need the correct item# for Leupold base to fit this rifle.

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