Don’t Get Screwed by Loose Screws!

Yep, loose screws will get you if you’re not careful.  When you buy a rifle, especially a rifle equipped with a scope, do you think all of the screws have been properly torqued at the factory or by the previous owner?  Don’t count on it.

I’ve worked on three rifles that came with scopes as a package during the last two years, and all three had very loose scope base and ring screws.  Those screws were so loose that I could easily turn them with a screwdriver bit between my thumb and forefinger. That level of looseness will absolutely affect accuracy. Would it surprise you that those rifles were a Remington 700, a Savage 110, and a Tikka T3? I also experienced it with a recently purchased Marlin 336 lever-acton on Gunbroker used for the pictures below.

I used to get worked up about rifles coming from the factory with loose screws but finally accepted the idea that it is my responsibility to ensure screws are properly torqued and my optic is mounted correctly. Besides, I like the idea of doing the job myself and knowing my rifle is in tip-top condition for hunting and target shooting. While you’re at it, do yourself a favor by turning your rifle upside-down and tightening the action screws, those larger screws that connect the stock to the receiver. You will find loose action screws are the second most common cause of poor accuracy next to loose screws around a scope. Here’s one example.

First, make sure you have the right tip on your screwdriver. It’s easy to slip and scratch your receiver or stock when using the wrong-sized screwdriver. Take out all screws and put them in a safe place as they are easily lost and difficult to find on the floor. Next, get some Q-tips and rubbing alcohol.  I use rubbing alcohol to degrease screws and tapped receiver holes because it won’t damage the finish on a rifle and dries very quickly. Dip a Q-tip into the alcohol and apply liberally to all threaded surfaces.

Use rubbing alcohol and Q-tips to swab and degrease all threads.

Oil and grease from tapped holes in the receiver. I bought this 1975 Marlin 336 from someone that had previously mounted a scope. I discovered lots of oil and grease on threads.

When you remove rings and bases, you will commonly find gobs of oil and grease on
surfaces that are better left dry.

Get some cotton balls and soak them with alcohol. Wipe off all surfaces of your rings and receiver around holes. Also wipe off the scope tube. DO NOT apply oil or grease to your rings or scope tube! They won’t rust because they are probably made of aluminum and lubrication will only increase the likelihood of your scope slipping in the rings. I can’t tell you how many times I’ve taken a scope off to find significant oil in the rings and on the scope tube.

You can find medium strength blue threadlocker at auto-parts stores and Walmart.

Grab some blue threadlocker and mount your scope base. I advise against using red threadlocker because it’s unnecessarily strong and makes removing screws in the future more difficult. Apply one drop of threadlocker to screw threads after degreasing. Again, be sure to use the correct screwdriver tip and tighten thoroughly. Mount your lower rings using the same method. Now it’s time to install your scope.

Use a bubble level to make sure your rifle is level. A gun vise of some type is very useful in this situation. Once your rifle is level, you can use the bubble level on your scope turret too. This makes it very easy to ensure your crosshairs are square with your rifle, an important part of making it easy to sight-in your rifle and make precise adjustments with tactical optics. Do not “eye ball” your cross-hairs to squareness with the rifle. You will undoubtedly have the scope and rifle out of square that way.

Level your rifle first. A gun vise is a big help here.

Mount your bottom rings, confirm the rifle is still level, then level your scope by using the top turret. Take off the cap which is often rounded on top and a poor surface for leveling.
(Don’t knock my vintage Tasco scope. That’s a 70s era Tasco made in Japan which is much better quality than today’s Tasco’s that are pure junk and made in China.)

Add threadlocker to your scope ring screws and tighten using a criss-cross pattern. Keep the bubble level on the top turret to ensure the scope does not twist while you are tightening screws. Try to maintain equal gaps between the bottom and top rings on both sides. Thoroughly tighten the screws, and that’s it!

While you’re at it, why not brighten up your front sight if you have see-through scope rings? Take some alcohol and swab the front sight post, then add a drop of nail polish to the bead or top of the blade. I typically use white, but you can use orange or any variety of neon. Don’t worry about messing up because you can use non-acetone based remover to take it off or touch up without harming your finish. Be careful to use non-acetone remover as acetone-based remover can damage your finish.



Taking the time to ensure your scope is properly mounted will save you headaches down the road. Tight screws all around your rifle, especially the scope and action, will ensure you are set up for accuracy.