I had a discussion today with some coworkers about using someone else’s rifle that has a red dot sight on it (eotech specifically). An issue was made with the gun’s zero. It was my contention that, if I was to qualify with my buddy’s rifle, I wouldn’t have to adjust anything–assuming that his RDS was zeroed.
His contention is that it IS zeroed, but it is zeroed to him personally. The way I understand red dot sights, without getting too technical, is that they reflect a light in such a way to produce a parallax free reticle–which means no matter how bass ackwards you position your eye/head/whatever to sight in on a target, your shot will hit where you see the reticle.
Now this is completely different from iron sights where your cheek weld, eye relief and an assortment of other things come into play.
Irons are sighted for the user. RDS are sighted to the rifle. If a rifle has a zeroed RDS, it’s zeroed for all operators. True/False?
Theoretically yes, a RDS zero should be good for most people but who knows. We are all built diferent and what I see when I look through a RDS or were I see the dot and how good I see it may not bee the same for the other guy. So general rule of thumb for RDS is do as you would with irons, zero it your self and dont take some one elses word for it.
I was always instructed that zeroing was aligning the sights to the weapons point of impact, not to a particular shooter.
What may make a rifle shoot slightly differently from one person to the next would be the sight picture used by the person zeroing…probably more so with irons. But for field use I would say that a properly zeroed weapon should be good to go.
Before the war started, the 82d started a Small Arms Master Gunner Course after having met with several other Infantry organizations at Benning. One of the events we did was to zero our assigned weapons with RDS and irons. Once that was complete we shifted one lane to the right and zeroed on another target with our buddies weapons. Not a single NCO had to change anything on either optic to get 5 out of 6 rounds consecutively within a 4cm circle at 25 meters.
The way it was explained to us is that every barrel and every set of optics are unique and have to be brought into alignment with each other to obtain the systems zero. I have demonstrated this many times with unbelievers by having them zero and qual with my assigned weapon.
One of our commanders at work pushed a “rack rifle” idea for her district late last year. The idea was have patrol rifles at the station just like the shotguns for everyone to use. She wants everyone to carry a rifle and we just don’t have enough. So a ran a rifle class in Dec of 2010 to try it out. Everyday I had the officers pick a different rifle and run the course of fire. Everyday it was different. Some were off and some were way off to where they didn’t shoot the 80% score needed to qual. It’s only out to 50 yards with the Transtar II target, but some were off the target. Even the other instructor and I shot the same rifle and the center of our individual 10 shot groups were about 3 inches different. Maybe for combat (center of man) accuracy it is fine, but I wouldn’t want to be responsible for that 100 yard head shot when I’m not certain of the zero. David
I know there is a small difference because of how it is zeroed. People don’t see the dot the same. Some people zero on the top edge, some zero through the dot, some turn the dot up to max some have it barely visible.
In practical terms I have had 3 different people all shoot my Primary Arms RDS sighted M&P 22 and all of them were hitting the same little flip target at 50 yards.
So I guess it kind of depends on your definition of “zeroed.”
I have encountered differences with irons, but that was usually due to different sight pictures between people, but that shouldn’t be an issue with a RDS.
An older US Army Marksmanship manual(80’s or 90’s), stated it was preferred to have the individual Soldier zero his rifle. But, it was better to have all rifles in the arms room zeroed by someone, rather then have some left un-zeroes, like unassigned weapons.
For much the same reasons, it eliminates the difference from barrel to sight.
Remember the gun is moving before the bullet leaves the barrel. So, how an individual holds the gun, controls recoil, etc. can all effect zero. That’s why sometimes your zero has slight changes from prone supported to unsupported, to bench, to kneeling, etc. Sometimes it small, or masked by crappy shooting in general.
Sometimes differences can be significant. I look at it this way, if the zero shift is only 1moa, if I’m a marginal shooter, that could be the difference from qualing and going home.
dwhitehorne,
I’ve been stuck in that situation. Another big issue, is responsibility. When no one is directly responsible for the weapon, it will be treated like crap. People will turn knobs, flip switches, and put cigarette butts down the barrel. They wont really care about cleaning it, PM ing it, etc either. Something else to think about.
I’d say definitely NOT. Yes in theory it should be on or close to on since it is BZOd to the rifle, but the issue of inperfect fundamentals comes into play. Im a Combat Marksmanship Trainer on the Marine rifle range, and more often than not, our Marines’ shots are far off to start with on BZO, sometimes totally off paper of an Able target at 200 yards. Sometimes it is definitely armory related, sometimes horrible fundamentals (damned POGs… oh wait I’m im a POG too) but sometimes its just different perception of sights. True, we use TA31 RCOs and not RDS, but nontheless its enough for me to never trust someone else’s BZO.
If both are competant shooters that percieve the aiming point the same and have a similar position, they will share a similar zero. I have tried this with a buddy of mine (zeroed, swapped rifles, checked zero), and I have accidentally shot someone else’s rifle (iron sights) during 300 yard rapid fire and didn’t know it until I saw my rifle leaning against the bench as I left the line (don’t worry, many pushups resulted from that error many years ago).
Some weapons will become more individually zeroed, especially if using a sling for positional stability with a non-floating HG.
If your shooting is within 200 meters, you would have to introduce a lot of variables, or one major value change, to make the zero questionable.
You left your rifle? For shame!
we play silly games when Marines do that, which involve disassembling the rifle completely and passing the parts out to my coaches. Good times.
RDS would work differently than ACOGs/scopes as far as all of the physics goes AFAIK, so they don’t really apply to this discussion. They’re not parallax free and would suffer from issues involving eye relief.
With Irons It may differ because of sight picture. Example someone putting nose on the charging handle vs. someone who keeps their head significantly back. With a dot sight no. It should be same same. The problem would come if people hold the dot in a different spot. Example on holds it high centered in the shoulders silhouettes vs. the lower ribcage area of the silhouette. The RDS is zeroed to the weapon.
Edit: It sounds like some of you are talking about iron sights or non-RDS. Of course those will be different and sometimes vastly different because of the limitations of those systems. I’m strictly referring to red dot sights like Aimpoints or Eotechs.
LWRC M6A1S with Troy irons and Eotech 552. Have to shoot the course twice, once with irons and once with the EO to qual. It is also interesting to see how much better some shoot with one system over the other back to back with the same rifle, but starting thread drift. David
I’m going to agree with F2S. Simply for the sake of what right looks like.
Even in the Army guys don’t know/have a set standard as to what the use as far as sight reference points.
Example being if Soldier A zeroes his irons using the top center of the front sight post in the exact center of the rear aperature that rifle will be zeroed to everyone that uses that exact method. Assuming it hasnt moved or been adjusted that is. Everyone will see the exact same thing through the sights.
An RDS makes this even more idiot proof in the fact that as long as you use the same part of the dot, (it doesnt even matter where its at in relation to the sight) its zero.
Exactly why firearms that have no adjustable sights worked back in the day. If everyone had the same method it worked.
The Army Research Institute at Benning conducted a study some time around 1979 and noted that a properly zeroed rifle will be zeroed for a great majority of troops who pick it up, sight unseen (I believe it was at 90+ percent confidence).
Differences occurred as Soldiers with glasses, astigmatism, or other optical differences picked up the rifles – yet were still able to hit E-type targets out to 200 yards.
Red dot sights will be much easier to hit with (assuming a properly zeroed rifle) since the shooter only has to concentrate on the dot instead of rear sight, front sight, and target.
I work for a small PD and we have three pool rifles (M4’s) with iron sights, but I have a personal M4 with an Eotech 512. During training (qualifications and training), I throw my rifle into the mix. We qual/train from 100yds on in and no one who has ever used my rifle has ever failed to shoot exceptionally well.
Also, no one has ever had a marksmanship issue with the pool rifle iron sights.
