[ED: Here’s an old Ask Foghorn post we still get asked about.]
Reader Jeremy writes:
I don’t know if you guys have gotten this question before, or if it would warrant writing an article, but do you have any feedback on zeroing a rifle on a range measured in yards, and then how accuracy would be affected when shooting that rifle estimating distance based on meters? The difference @ 100m vs. 100 yards is going to be about 9′ so my assumption is that even to the max effective range of a 5.56 round, there isn’t going to be enough of a difference to see a noticeable POI shift. Do you have an opinion?
Good news for the lazy among us: for the typical zero on a 5.56 gun, it doesn’t really matter.
Meters are longer than yards, but only by a tiny bit. For one meter or ten meters, it’s virtually the same. In fact, the difference between meters and yards at 50 yards is negligible. Which is perfect for our purposes.
The typical 5.56 rifle zero is a 50 yard/meter zero. That puts the round on target at 50 yards and 200 yards, with less than a three-inch vertical deviation over that distance. It’s also the zero that’s used with Leupold and Trijicon’s optics, as zeroing at 50 yards will align the trajectory with the reticle.
At 50 yards, the difference between meters and yards is still so small that it really doesn’t matter. In fact, the inherent inaccuracy of your barrel and ammunition will probably do more to mess with your zero than the difference between yards and meters (more about that here).
In fact, even at longer distances the difference still really doesn’t matter. Doing the calculations in either metric or imperial units will get you close enough to where you can walk the shot on target with a couple of rounds.
If you’re going for precision shooting, though, it might matter. But if you’re the “one shot, one kill” kind of person, you already know your holds (or can calculate them) in either system and adjust as needed.
For new shooters, my advice is not to sweat the small stuff. Even for NRA High Power service rifle matches, I calculated my ballistics in yards while the range at MCB Quantico is laid out in meters and it didn’t slow me down. Two sighters and I was tapping the X ring.
The difference between meters and yards is important, and for those who need to make a precise shot, it’s important to understand the difference and adjust as necessary. But for those just starting out, it’s no biggie.