Home Forums Hunting & Shooting Handguns MRDS Zero

Something I've been working on and thought it would be useful to the group since so many threads on MRDS pistols have come up lately. It's great to learn. Knowledge is power.

Short version... Zero at 25 yards. Zero'ing at 10 yards is for people who can't shoot. Don't be that guy.

Long version...
The 10 yard zero is common and very popular among MRDS instructors. I believe that's for a couple of reasons--They don't want to embarrass students who can't hit a zeroing target at 25 yards, it takes longer to manage a line of students at 25 yards than 10, if they promote a 25 yard zero they'll be mocked and ridiculed by all the people who can't hit a zeroing target at 25 yards (which is the overwhelming majority of people).

Those that promote the 10 yard zero often cite the very slight difference in bullet trajectory (elevation) between a 10 and 25 yard zero at any sane defensive shooting distance. And they're correct that the trajectory (elevation) differences are negligible.

However--What we've found is that people can't, and don't, shoot a 10 yard group precisely enough to KNOW that they're zero'd at 10 yards. Being very slightly off on your 10 yard zero manifests in significant ways at 25 yards. When you zero at 10 yards are all of your shots exactly on the horizontal line of a 10 yard zero? Or are some of them scattered slightly above and below that perfect 10 yard zero line? And does that slight scattering matter? Foreshadowing...It does. And double foreshadowing...It matters just as much for windage.

Today I fired 10 round groups with a stock M&P with an Aimpoint ACRO and got a "good" 10 yard zero on it, with Speer Gold Dot and Speer Lawman ammunition. Then I fired another group at 25 yards to see how much, if any, deviation was present. There was quite a bit.

This 10 yard group is what I would call "zero'd", but if you look at it very closely you'll see that 20% of the shots are slightly left of true zero and 40% of them are slightly right of true zero. And that very slight (less than .75") shift to the right manifested in 40% of the shots being nearly 2" off zero at 25 yards.



With practice ammo the 10 yard group was larger, but was still a 10x group scattered evenly around the 1.69" X ring. But if you look very closely 70% of the shots are actually to the left of the true zero. The 25 yard group's center was approximately 2" high and 2" left of zero. The practice ammo is inherently less accurate already, so the much larger 25 yard group really shows how a 10 yard zero can translate to misses at 25 yards.

Good post, and it’s the same reason a 25’ish yard zero with an AR isn’t ‘good enough’. Small differences too hard to detect at 25 show up at 100+.