.

Somebody posted this video a while back and there was some lengthy discussion about it.  In any case, pretty good information here. 

I personally have ARs with red dots (no magnification) zeroed at 50 yards to match the ballistic capabilities of the 5.56 round and it's effective range (or at least what I view as effective range for my needs).  I've gotten used to the hold overs up close and how the POI changes between 50 yards and out to day 200-250 ish yards.  Others may select different zero for their use or preference, but in the end, I think you just pick one that you believe fits your use/needs and learn it. 

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I'm a big believer in the 50/200 zero

I wonder what the effective combat zero of my mosin will be...

Somewhere beyond the effective range of a rock throw?   

Interesting.  I guess you could try zeroing at say 50 and 100 and for each zero, set a target at 25, 50, 100, 200 and 300 yards.  But that sounds like a lot of work and ammo. . . so when are you doing the tests?   

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Man these guys make it look easy.

It took me a long, long time to wrap my head around this idea.  And I finally decided that it's because the whole concept is just mislabeled.  And because of this prevailing idea that there's something magical about any particular distance (ie 200 yards).

If anyone cares, here's how i finally figured out what's going on.  If noone cares, stop reading now! 

Imagine we have a nice, 100% flat shooting, perfectly horizontal shooting range that's 5,000 yards long.  And along that range, every X yards, we have a target stand.  On each target stand, there is a bullseye of Y inch diameter.  And these targets are all aligned with laser precision to within one quintillionth of an inch.

Now we take a gun, any gun.  And we mount it by the muzzle to a cradle that can pivot vertically.  And we put that cradle so that the muzzle is in contact with the center of our first target.  This mounting system can rotate so that the gun can fire straight up, straight down, and every angle in-between.  And the muzzle of the gun will always be aligned with the center of the 0 yard target. 

Obviously, if the gun is vertical, there will be no hole in any target.  But if it is tilted forward, the first hole will always be in the center of the 0 yard target.

Now, let's start with the gun perfectly horizontal and fire a round.  Perfect center of the bullseye on the first target, and as it moves out, the holes hit lower and lower on each successive target until the bullet is passing below the bullseyes.  Simple enough, right?

Slowly tilt the gun upwards, a degree at a time, firing a round each time.  The bullet holes begin to rise through the first few bullseyes, then drop again.

At some point, the angle up is enough that the bullet actually begins to pass above some bullseyes before dropping again. 

As you continually increase the tilt, the bullet will travel farther, and the shape of the curve it's following will change. 

Then, at some point, the range will again begin to fall off, but the shape of the curve will continue to change, until eventually, the gun is vertical, and the curve has flattened to a line.

Somewhere in there is a curve such that the bullet is impacting the maximum possible number of bullseyes.  And that's what we're talking about!

I made this little drawing... probably should have just posted this instead of trying to say it all.  Notice how on the 3rd image from the top, the bullet's flight passes through 4 bullseyes at the far end of its flight, while other angles have less success.

Tom,

Check this article out.

http://aesirtraining.com/home/rifle-zero/

I didn't catch the last discussion on the topic but with all due respect to Travis as I call him a friend, some of his numbers are messed up. 

I didn't catch the last discussion on the topic but with all due respect to Travis as I call him a friend, some of his numbers are messed up.

Would you be kind enough to share what numbers you're referring to?

 

It took me a long, long time to wrap my head around this idea.  And I finally decided that it's because the whole concept is just mislabeled.  And because of this prevailing idea that there's something magical about any particular distance (ie 200 yards).

If anyone cares, here's how i finally figured out what's going on.  If noone cares, stop reading now! 

Imagine we have a nice, 100% flat shooting, perfectly horizontal shooting range that's 5,000 yards long.  And along that range, every X yards, we have a target stand.  On each target stand, there is a bullseye of Y inch diameter.  And these targets are all aligned with laser precision to within one quintillionth of an inch.

Now we take a gun, any gun.  And we mount it by the muzzle to a cradle that can pivot vertically.  And we put that cradle so that the muzzle is in contact with the center of our first target.  This mounting system can rotate so that the gun can fire straight up, straight down, and every angle in-between.  And the muzzle of the gun will always be aligned with the center of the 0 yard target. 

Obviously, if the gun is vertical, there will be no hole in any target.  But if it is tilted forward, the first hole will always be in the center of the 0 yard target.

Now, let's start with the gun perfectly horizontal and fire a round.  Perfect center of the bullseye on the first target, and as it moves out, the holes hit lower and lower on each successive target until the bullet is passing below the bullseyes.  Simple enough, right?

Slowly tilt the gun upwards, a degree at a time, firing a round each time.  The bullet holes begin to rise through the first few bullseyes, then drop again.

At some point, the angle up is enough that the bullet actually begins to pass above some bullseyes before dropping again. 

As you continually increase the tilt, the bullet will travel farther, and the shape of the curve it's following will change. 

Then, at some point, the range will again begin to fall off, but the shape of the curve will continue to change, until eventually, the gun is vertical, and the curve has flattened to a line.

Somewhere in there is a curve such that the bullet is impacting the maximum possible number of bullseyes.  And that's what we're talking about!

I made this little drawing... probably should have just posted this instead of trying to say it all.  Notice how on the 3rd image from the top, the bullet's flight passes through 4 bullseyes at the far end of its flight, while other angles have less success.

wassup Tom_G, lol brother your chart reminds me of the technique I use to water my grass when I need to get to the spots that I can't quite get...

But it's helpful. That's for the knowledgeable post.

Would you be kind enough to share what numbers you're referring to?

 

Sure.  Some are potentially just a variance in shooting or bad shots, but I have shot long range precision with Travis and he is a shooter with a lot of real world experience so I don't think some of the results are performance issues.  Other issues are just plain mistakes. 

First example from the 25 yard zero would be the 400 yard shot.  We need to understand that yards and meters can be critical especially at certain ends of the range of shots.  His other shots from 50 to 300 yards are consistent with a 25 yard or 25 meter zero, however his 400 yard impact is approx a minus 7 inches (-7.0") below the line of sight which is consistent with a 25 meter zero.  A 25 yard zero would produce an impact that would still be in the +0.5" range or just above the line of sight prior to the second crossing point.  So either he mis-stated his type of zero or he is off target by more than 7".

Second example would be the 100 yard zero.  The 100 yard zero with the AR15/M4 platform of rifle is a bit unique in that it really is only calculated as one meeting point of the bullet into the shooters line of sight.  In other words with the 100 yard zero the bullet only achieves its max ordinate (highest point in its trajectory) as it brushes along the line of sight.  In reality that bullet actually does go above the line of sight but by only about +0.010" and that is only for a flight distance of about 10 yards or so.   This is calculated with M855 ammo, but all ammo in the .223 or 5.56 no matter the grain / load will produce very similar results.  So what does this mean?  This means that with a 100 yard zero there will be no impacts higher than the 100 yard zero.  Travis has the 50 yard at +2.5" high and the 25 yard at +2.8" high.  This is simply NOT possible and Travis should have recognized this.  This is not just an ooops moment but that knowledge is Barney basic information that he should have recognized.  In reality it looks from the impacts that the top impact would be more likely the actual 100 yard impact, the next lowest would be the 50 yard impact at -0.8" and below that would be the 25 yard impact at -1.5" which makes perfect ballistic sense in that order.  I think they messed up on marking the impacts.  Also the 300 yard impact should be around -10.0" not the -18.0" or so that he shows and the 400 yard should be around -24.0".

For the 200 yard zero, it would have been easier to say that it mirrors the impacts in the 50 yard zero.  This is the case because the with a 50y/200m zero the bullet crosses the line of sight at nearly the exact same points.  Therefore they are virtually the same zero's with the same results for impacts.  If you notice the impacts are pretty much the same but he did not show the 25 yard impact on the 50yard zero target.  This somewhat puzzles me as to why he specifically mentions that he is intrigued by the 200 yard zero when it is virtually the same thing as the 50 yard zero.  In reality it is called the 50/200 zero.  Some think it is 50 yards and 200 yards but it is really closer to 50 yards and 200 meters and commonly referred to as the 50/200 zero.  He knows this, which is why I am a bit confused by his delivery on the video.

Lastly there is the same issue in the 300 yard zero which he mentions 36 yards as the first crossing of the line of sight of the bullet trajectory.  If the bullet is going on its ascending branch of flight (going uphill) it crosses line of sight at 36 yards.  Again it is IMPOSSIBLE to have a 25 yard impact that is higher than your line of sight or higher than your 300 yard zero.  He shows the 25 yard impact at approx +1.5".

While this does not mean a great deal when we are talking "combat effective" impacts or zones, but it does show quite a bit of basic marksmanship flaws which could be due to shooter error, or not marking the correct holes with the correct distances.  As for having impacts that show too high, it is IMPOSSIBLE and Travis should have easily recognized this mistake and maybe should have questioned if they perhaps mislabeled the targets.  So either he didn't catch it, or they didn't want to mess up their target by re tagging them, or having to re shoot them.

very informative discussion