You hear “MOA” a lot in the firearms industry. Some of you may already know what it stands for and how it works. For those who don’t, I hope to offer an explanation that will help guide you through future purchases or gear selection etc.
M.O.A. stands for Minute of Angle. When you see this regarding rifles, it’s often “1 MOA accuracy guarantee with match ammunition”. What they are referring to is how accurate the rifle is. They are saying, “We guarantee that this rifle will shoot a 1.047” group or better at 100 yards with match/premium ammunition.” The standard for factory rifles with this type of guarantee is usually 3 rounds.
Now, to get more specific, there are two types of MOA – TMOA and SMOA. TMOA stands for “True Minute of Angle” and SMOA stands for “Shooters Minute of Angle”. SMOA and Inch per Hundred Yard (IPHY) is the same thing and represent 1” per 100 yards. A True MOA (TMOA) equals 1.047” per 100 yards. It is particularly important knowing which your scope uses, especially when shooting long distance.
While shopping for a scope base, it’s common to see “0 MOA cant” or “20 MOA cant”. They are referring to the amount of downward slope the scope will be mounted. An angled scope base will allow you to use more of the scope’s available movement, meaning you can dial elevation for farther distances before you have to hold over the target. In some cases, if your scope bottoms and you cannot zero at 100 yards, an angled scope base with more cant (ie. 30 MOA or 40 MOA base) will fix the issue.
Minute of Angle regarding rifle scopes is used in reference to a couple things. Most commonly, they are referring to the unit of angular measurement the scope uses to adjust. When you are sighting in a rifle, it will say “1/4 MOA” on the elevation (up and down) and windage (left and right) turrets. This tells you that each click moves the scope 0.26175” at 100 yards. Next, is the scope reticle. MOA will be referenced when breaking down different holdover and windage points on vertical and horizontal lines of the reticle. For example, with your rifle zeroed at 100 yards and knowing the first dot on the lower part of the reticle is 6 MOA, then we know at 100 yards the holdover of the target is 6.282”. This information can be used to shoot targets at farther distances. Lastly is travel; when looking at the rifle scope’s specs, they will list the amount of total movement for the elevation and windage turrets. This will typically read “100 MOA elevation” and “60 MOA windage”. The more elevation travel in a scope, the farther you can shoot before needing to holdover. But remember, 100 MOA total travel on the spec sheet doesn’t mean you will have 100 MOA of elevation from your 100 yard zero.
Ammunition also sometimes references MOA. Similarly to rifles, they are typically referring to accuracy performance. Match ammunition or other types of premium ammunition may advertise a “1 MOA accuracy guarantee”. What they are saying is, “this ammunition is capable of shooting 1.047” group or better at 100 yards.” You may also notice information on the box where they estimate how many MOA to dial into your scope or holdover with the reticle and reach targets at different distances. This is a rough estimate.
Rifles, scopes and ammunition can be a deep “rabbit hole” and we’ve only scratched the surface in this article. I hope this information helps you understand what is meant when you see “Minute of Angle” referenced in rifle accuracy guarantees and the long spec sheet of the latest rifle scope. MOA is simply an angular measurement but the context changes a bit depending on what exactly we are talking about. If you continue deeper down this path, you will eventually begin talking about mils and ballistic coefficients!