Torque - Like Goldilocks, you want it "just right"

Short version:

  • #6-48 screws - 20 in-lbs, and use blue or purple loctite for best results.

    (For X-BOLT actions only -- The (4) front screw holes are very shallow, so only use 10 in-lbs on those (4) screws.)

  • #8-40 screws - 30 in-lbs, and use blue or purple loctite for best results.
  • Alternative method: Tighten screws until snug (~3-4 in-lb), then tighten another 1/4 turn. This will get you very close to the target tightness range.

Long version:

All base mounting screws need to be tightened "enough". If you don't get them tight enough, bad things like having your scope mount come loose or even fall off can happen.

The two main techniques to ensure this doesn't happen is to 1) Tighten them sufficiently so the screw stretches elastically, or 2) apply a thread locking product to the screw (Loctite, etc). Even better, combine them, and apply thread locking compound to a properly tightened screw.

Ok, you're probably thinking "I don't want them too loose", I'll just tighten the snot out of them." While that sounds like fun, you'll soon run into trouble when the heads of the screws fail and fall off, leaving you with just the threaded shank, possibly stuck in the hole.

The goal of all torque recommendations is to establish a repeatable amount of stretching of the screw, stressing it to 60-80% of it's yield strength. This will ensure the greatest possible clamping force, while avoiding bad things like head separation, or stripping of the threaded surfaces. The stretching of the screw enables it to stay tight, even when shock loads (like rifle recoil) work against it. This prevents loosening and unscrewing from happening during vibration.

Now that you know that you want the screw to stretch some, how do you actually achieve this "just right" level of stretch? You can either tighten the screw to a preset torque value, or you can tighten the screw a controlled amount past "snug". Personally, I recommend tightening the screw approximately 90 degrees, or 1/4 turn past "snug". This will stretch the screw to roughly 65% of it's yield strength, without requiring an expensive, possibly inaccurate torque wrench, or being dependant on thread lubrication. The main downside to tightening by "Torque value" is that the actual stretching of the screw for a given torque level depends greatly on the friction between the threads. 15 in-lbs applied to a perfectly clean and degreased screw, in a perfectly clean hole might only allow for 60 degrees of over-rotation, and a looser than optimal screw. In contrast, a screw lubricated with a high quality, EP grease might allow for 120 degrees of over-rotation for at the same 15 in-lbs, resulting in a screw that is close, or at the point of failure.

When in doubt, tighten less, and use thread locking compounds. If at any point while tightening the screws the force required starts to go down, STOP!!! You are either stripping the threads, or the screw head is beginning to fail. Carefully back-off and remove that screw, and throw it away. It shouldn't be reused. If you doubt your screws, or need a replacement, please contact us, and we will be happy to supply replacements.