At some point or another I get a question about what distance to zero a pistol mounted optic in our courses. Followed closely by how to zero the optic to the desired zero distance.
Point Blank Range
The big question is what distance will you zero? There are a lot of factors to consider on this topic. Similar to the maximum point blank range for the rifle I want to know the maximum vertical spread without any shooter applied adjustments. In other words, if I were to make no adjustments or holds at what distance will the trajectory deliver the round out of the target zone. For the rifle, we use an 8 inch target zone, but for the pistol I want a 4 inch target zone and here’s why. The target zone size for our headshots is 4 inches and if I make no adjustments with certain zeros at certain distances I will miss. The magic number is 2 inches, I have 2 inches of vertical spread to play with when it comes to choosing a zero distance. If the point of aim remains constant, that means 2 inches high and 2 inches low for the point of impact. When the trajectory of a certain zero exceeds the point blank range within 0-25 yards it is inferior to those that do not. The most popular zeroes are 25 and 10 yards, with 15 yards gaining in popularity. The shift in point of impact at 5 yards and closer with these zeros is negligible with the main issue being the actual height of the optic. It is when we push out to further we can see issues.
Next is how good of a shot are you when it comes to shooting your pistol. If you cannot shoot a tight group at your desired zero distance it doesn’t matter how good the zero distance is according to the internet. Which is why I will sometimes suggest the 10 yard zero, most shooters can repeatedly deliver 2″ groups at the 10 yard line. Thus allowing us to more quickly get to the meat of the curriculum. If the shooter can repeatedly deliver 4″ groups at the 25 yard line then I recommend they exploit as much of the red dot’s capability as possible. Regardless of which zero you choose, you must shoot at all ranges to see the difference in POA/POI. Typically, when I finish my zeroing procedures I will shoot 3 rounds at 20, 15, 10, and 5 yards to see the maximum vertical spread. If I have time, I will do the same at 35 and 50 yards.
Duty or Training Ammunition
Once you’ve settled on a zero distance, the next step is to actually zero the optic to the pistol. It is a good idea to bring the optic’s owner manual as a reference, along with any optic specific tools to the range. Ensure the optic is properly mounted and tightened to manufacture specifications. After you complete your zeroing process confirm the optic is still secure and apply witness marks to the mounting screws. Ideally, you will want to zero with the defensive or duty ammunition you will carry. My average zeroing session will require 20-25 rounds or 6-8 volleys to complete the process. It may seem like a waste, but I find it better to zero with my defensive ammunition then perform a range familiarization with my training ammunition. Typically, defensive ammunition is heavier, hotter and more precise. As a result, it will shoot to a different point of impact than the lighter and slower training ammunition. If we are trying to be as detailed as possible, this matters. Should you use a supported position to help eliminate shooter error? It depends. If you can get into a comfortable position while maintaining the straightest line of sight through the optic to the target then yes. If no, freestyle will have to work. If I don’t get the same head position when supported I see the dot differently and that can mess with my zeroing. And speaking of seeing the dot, make sure you are focused on the target. To help stay target focused lower the dot’s intensity when zeroing or rezeroing. Remember to return to your preferred intensity when finished and engage any button lockout features.
Regardless of the zero distance I start with a spotter group at the 5 yard line. I know at the 5 yard line my impacts should be about 1.5 inches low for a 25 yard zero. If this is the first time mounting and zeroing said optic it can save you a lot of heartache and ammunition. You can use other methods such as a laser boresight, but I can’t get them to work in my micro compact pistols so I stick to this procedure for all my pistols. What I’m really looking for is windage. I want my windage to be dialed in super tight. I find when I start at the 5 yard line, any windage adjustments I have to make at the 25 yard line are minor. A quick note on groups, how many rounds should you fire? Again that depends on you and your accuracy capacity. If you are consistent, then 3 rounds is good. If you are still working on your consistency then 5 rounds gives you more of a buffer should you have some flyers. Now, here is where I make an argument for which zero distance is “better”. The corrective value of the optic. If I’m using an optic with a corrective value of 1MOA at 100 yards then at 25 yards, one click will adjust the impact ¼ inch. I can be very precise and quick. Same optic with a 10 yard zero will have a 1/10 corrective value. I don’t see the same level of precision with this distance for some reason. With other zeros there is a bit of a guessing game. Sometimes, you get to a point where it is good enough because the corrective value doesn’t cleanly fit.
The Devil Is In The Details
Once I get to the zero distance, the real work begins. Review the 5 Marksmanship Fundamental Principles and be as consistent as possible. Consistency is the key, the more consistent you are the more accuracy you can achieve. Here is one advantage for the 15 yard zero in my opinion. It is just far enough I can see the first and second groups before I have to go down range to tape. It can expedite the process, especially in large groups such as a class. Even then, I still prefer the 25 yard line. My process is pretty simple, I shoot and call as many shots as possible. Calling your shots is super important since it allows you to manage any flyers. If I call a shot and know one went high or wide, when I observe the target I’m looking for an impact in that general location. Then observe and measure the results. I measure from the center of the group and write down the distance to center. I suggest working with elevations first, windage should be close. I also suggest making corrections for only one direction at a time. I know this can be time consuming, but if we are dealing with major corrections, something larger than the point blank range it is a good idea to get one done at a time. Once I write down the distance in inches, I then convert to the number of clicks needed to adjust the point of impact. Again, this is where the 25 yard zero with a 1MOA optic really shines. Double check your work, then tape the target. Before you input the corrections, make sure you know the correct turret and direction for the desired input. This is why it is nice to write the corrections down, you don’t have to remember them. Plus, if you notice a massive shift in the wrong direction you can refer to your notes and help diagnose what happened. Perform the desired number of volleys until you are satisfied with the results.
I like to confirm my zero about 2 or 3 times a year or if I change anything. If I replace the battery and have to remove the housing, then definitely. As far as how often to replace the battery. Read the owners manual regarding low battery alerts. I routinely replace the batteries in my primary carry and home defense pistols once a year. All other optics when necessary. If I have to use different type of defensive ammunition for whatever reason I re-zero or confirm the shift in POI. If you live in an area with extreme weather shifts you might want to rezero as the seasons change. I clean my optic’s window at least once a month, sometimes more depending on what’s happening. You would be amazed how much dirt, dust and other debris can build up on your lens. If it is an open optic it is a good idea to blow any loose debris out of the housing. The last thing I do is check the witness marks on the mounting screws. If I notice a shift of any amount I stop what I’m doing. Retighten the mounting screws to factory settings. Then at my first opportunity reconfirm the zero or if necessary rezero.
Zeroing is cathartic to me, I enjoy the process no matter the platform. It allows me to be very detailed oriented and while some may question the need, that alone is a major difference.