When you buy new scope rings, they are usually not perfectly aligned and often quite rough on the inside, which can scratch your scope tube due to the metal-on-metal contact. This is because creating perfect scope rings is very expensive, and unless you’re happy to spend $130 or more, you’re unlikely to be able to acquire a premium set. But fortunately, there’s an easy fix for this issue. Let’s explore how to lap scope rings to prevent scope tube damage.
Most scope tubes are made of thin aluminum, if and you clamp a ring that isn’t perfectly round or smooth to your tube, it can be damaged significantly. In fact, if they are very rough, your rings can even bind up the moving parts of your magnification ring, the gears, or the moving parts of the elevation and windage turrets. What’s more, if your rings are not properly lined up, the tube can be bent out of shape, which further impairs your scope’s accuracy.
Despite all this, many weekend warriors don’t deem it necessary to lap their scope rings before use. Although this may be okay with a $50 scope that’s made in China, it’d be a shame to damage a more high-end one, especially as the issue can be avoided very easily. If you don’t know any rifle enthusiasts who can demonstrate the process to you, reading and maybe watching some videos should be enough to get you started. Even someone who’s never done it before or even seen it in action shouldn’t have too much trouble lapping scope rings, as long as the set-up is correct and of a high enough quality.
Prior to explaining the details of lapping your scope rings, let’s discuss some important factors to keep in mind. Firstly, there is a common misconception that the heavy texture of the inside of your scope rings helps them to grip to the scope. This is not true, and the only reason that they come like this is the manufacturing cost associated with making them perfectly smooth. Don’t worry, you will not damage your rings by lapping them.
Also, always keep in mind that once you’ve lapped your rings, you can no longer switch them out. That’s why it’s vital to mark them, and although you can do this with masking tape during the process, it might be helpful to write on the actual rings in a permanent marker for future reference. Finally, remember that you’ll need to take off about 80% of the rings’ polish, so make sure you’ve got enough time to complete several rounds of lapping.
You’ll have to buy a lapping kit before you begin, which may cost around $70-80. Don’t simply go for the cheapest option, but make sure that you buy a quality kit, for example, one from Sinclair, Midway, or Brownells. Check that your chosen kit includes a lapping compound, and if it doesn’t, you can buy some 800-grit compound at your local DIY store.
After lapping, you shouldn’t switch out your rings or even reverse the way they sit, so make sure to label them ‘front’ and ‘rear’ beforehand. You can use masking tape once you’ve attached them to your rifle. Next, remove the ring screws and top halves and cover up the action so that none of the lapping compound will fall in by accident. Smear the compound on both the upper and lower halves of the rings, then place the lapping rod onto the lower halves.
You can now replace your rings’ upper halves, but don’t tighten the screws as you’ll need to be able to move the rod. Once you’ve completed all of these preparatory steps, you’re ready to work the lap.
Turn and slide your lapping rod back and forth to start lapping your rings. Initially, this will be easy as the worst bumps are removed, and you’ll have to tighten the ring screws frequently. As you continue the process and get closer to the desired smooth shape, it might start to take a little longer. It is recommended that you reapply the lapping compound after about 30 back-and-forth motions, which is approximately the equivalent of two radio songs.
Make sure to apply more compound regularly when lapping, unscrewing the rings each time to do so. This is a good time to wipe off your rings and check on progress, ensuring that you’re not taking off too much material. Most people recommend repeating the lapping process two to five times, but it will depend on the condition of your scope rings and what material they are made from, which is usually either aluminum or steel.
In most cases, you can stop lapping when around 80 percent of the lower rings’ surfaces are perfectly smooth and true. It should be slightly less than this for the upper surfaces. Make sure not to take off too much material, as this could stop your rings from gripping the riflescope properly once you’ve tightened the screws.
When you’re done with the lapping process and satisfied with your result, you’ll have to wipe and rinse the rings off to get rid of all the lapping compound. Screw your scope onto the rings and observe the difference. Everything should now be true and fit together perfectly. Check that the screws all come snug at the same time, as this indicates that your scope’s tube is no longer being contorted out of shape.
Although it’s not the most glamorous part of your rifle, a scope that functions smoothly and gives you an accurate, clear picture is priceless. Rough or inaccurate rings are one of the biggest issues related to your scope, but luckily, there is an easy and quick way to fix this by learning how to lap scope rings. That way, you are ensuring that all the moving parts inside your scope are functioning perfectly and preventing any potential damage to the tube.