Why Do You Need a 20 MOA Scope Base?

There are a number of differences from normal shooting and long range shooting. One of the most impactful differences is the mounting of a scope. This applies to the 20 MOA scope base versus a 0 MOA scope base.

Why should you use the 20 MOA version and how does it impact your shooting? We are going to go over that today. 

What is Mechanical Offset?

The mechanical offset of a scope is the space between the center bore axis of the gun and the center of the scope. Generally, for normal rifles like the AR-15 or guns with similar usage the mechanical offset matters at the closer ranges they are used in.

This mainly is from the use of a 0 MOA scope base. Using a 0 MOA scope base keeps the bore and the scope center parallel to infinity before taking into account the bullet drop. This provides a good reference point for shooting out to 300 to 500 yards. But beyond that things start to get tricky.

How Your Scope Base Affects Long Range Shooting

At the 600 yard range, we start to see some problems with a 0 MOA scope base. Since we have to angle the rifle upwards to get the trajectory we need to hit targets at that distance, we need to know just how much of an adjustment is needed in the scope to consistently hit that range.

Now most scopes can reach 600 yards or farther without the additional 20 MOA a canted base will provide. However, adding a 20 MOA scope base will place your scope centerline at 600 yards allowing you to be able to reach beyond 1000 yards more easily.

Keep in mind this assumes your ammunition can reach that far and you know the “dope” of your load with your particular rifle setup.  This includes knowing how far your adjustments can go.

Making the Most of Your Scope Adjustments

Generally you can take the maximum adjustments of your scope and divide it by half. This is roughly the amount of adjustment you will get with a 0 MOA scope base. Your adjustments will be fine below 1000 yards but you’ll start to run out of scope adjustment the closer you get to 1000 yards.

Using a 20 MOA base adds extra space to use your elevation more efficiently. This will extend your adjustments beyond 1000 yards by several hundred yards depending on your loading data. Essentially, the more your scope base adjusts for, the more usable elevation adjustments you have.

Conclusion

If you are getting into long range shooting you should have a 20 MOA scope base. It makes the scope more usable at long distance and it provides a strong foundation to build your skills on without having to swap out a mount that you started with.

Don’t know where to start looking for your 20 MOA base? We have a number of Talley brand scope bases and mounts available to choose from. Be sure to match the correct rifle style and scope size before purchasing.