Gear, Parts and Accessories

Maximum Point Blank Range and the Battlesight Zero

The MPBR is the maximum range at which the bullet rise and drop stays within the vital area of your target. Anyone who has been in the U.S. Army or Marine Corps is familiar with a battlesight zero or improved battlesight zero (BZ0 or IBZ0). The concept for an MPBR or battlesight zero is pretty much the same: zero the rifle so that you get a point of aim that is effective over the longest range. The battlesight zero used by Marines when shooting the iron sight M16A2 is the 36/300 zero, meaning that the bullet will be on the sight line at 36 yards and again at 300 yards. The US Army uses what is referred to as an improved battlesight zero, which calibrates the rifle to be dead on at 50 and at 225 yards. The USMC also uses the 50/225 IBZ0 for M16A3 rifles equipped with Trijicon ACOG scopes.

The illustration above demonstrates how a battlesight zero works. The bullet is fired from the barrel and rises up to be exactly on the line of sight at 36 yards. It then continues to rise, topping out at 6″-7″ depending on the round used and the barrel length of the rifle. It then descends until it is again exactly on the line of sight at 300 yards. This gives the Marine a good aiming point for a man sized target at any distance between 0 and just over 300 yards.

From the USMC manual:

If a rifle is zeroed for 300 yards, the bullet crosses the line of sight twice. It first crosses the line of sight on its upward path of trajectory at 36 yards, and again farther down range at 300 yards. Since a bullet crosses the line of sight at 36 yards and again at 300 yards when a rifle is zeroed, a rifle’s zero may be established at a distance of 36 yards and the same zero will be effective at 300 yards. It is critical that a Marine fires tightly grouped shots directly on the point of aim when establishing a BZO at 36 yards because any error in shot placement at 36 yards will magnify as the bullet travels down range. If the rifle is properly zeroed for 300 yards/meters, the trajectory (path of the bullet) will rise approximately 7 1/2 inches above the line of sight at a distance of approximately 175 yards/meters. At other distances, the strike of the bullet will be less than 7 1/2 inches above the point of aim. Only at 36 yards/30 meters and 300 yards/meters does the point of impact coincide with the point of aim. If only a portion of the target is visible (e.g., the head of an enemy soldier), the trajectory of the bullet may have to be taken into consideration when firing at a distance other than 300 yards/meters. If a Marine does not consider trajectory, he may shoot over the top of the target if the target is small and at a distance other than 300 yards/meters.

The 50/225 IBZ0 is useful as the bullet has much less rise at the midpoint of the trajectory. Its shorter effective range is more suited to urban and jungle warfare where visibility is limited and most engagements are at close range. The fact that the bullet rise is lower means that shots taken at ranges between 0 and 250 yards are much more accurate, with a bullet rise less than 2 inches at the midpoint of the trajectory.

The battlesight zero as a concept is very useful to hunters as well. When hunting deer, or any medium sized game, it is rare to know the exact distance that the quarry will be encountered at. Luckily, if your rifle is properly sighted in for its maximum point blank range (MPBR) you don’t need to know the exact distance. While the ballistics vary from rifle to rifle, it is generally a simple matter using any number of online ballistic calculators to work out what the ideal zero for your rifle should be. The most critical calculation is your second zero. Based off of the size of the vital area of your target, you can compute the maximum rise and drop tolerable for your cartridge. Most white tail deer for example have a vital area that is generally 10 inches in diameter. Mule deer, elk, and moose have vital areas that are significantly larger. A large mule deer has a vital area around 12″ in diameter, an average elk around 15″, and a good sized moose nearly 21″. A hit from a medium caliber rifle to this area will result in a quick kill. Therefore, if we are hunting white tailed deer, we can tolerate a maximum rise and drop of 5″. Using this value, it is simple to calculate that the MPBR for a 180 grain Remington Core-Lokt .308 roundnose soft point cartridge in my trusty Remington 700 is 293 yards, with our second zero at 252 yards. With our rifle zeroed for these distances, we can be assured that a perfectly centered aim on a deer at any distance between 0 and nearly 300 yards will result in a hit in the vital area of our target.

The problem with zeroing your rifle for 293 yards in this case is that not many people have access to a 300 yard range. Not to worry, there are other ways to achieve the same zero for your hunting rifle. As it mentions in the USMC manual we referenced above, you can sight in your rifle at a closer range for the same result. In fact, if you have a good bench rest and a gridded target you can, with a little math, perfectly achieve a MPBR zero on your rifle at any range. Lets assume for this example that our range only has a 50 yard rifle range. We’re shooting a Remington 700 chambered in .308 and plan to use the 180 grain Remington Core-Lokt mentioned above. By plugging in the information for that load, we can see that the bullet should hit 2.2″ high at 50 yards (if you were at a 100 yard range, it would hit 4.45″ high). Our first zero for this rifle and cartridge combination is actually just shy of 20 yards, and you can use that distance if that is the only range available at your local shooting gallery, but be aware that minute errors in measurement which may not be apparent at that close range will be magnified at longer distances, possibly throwing your shot off.

Remember: The Battlesight Zero and Improved Battlesight Zero discussed here only work on 5.56 M16 and AR-15 style rifles. You will need to find the maximum point blank range for your unique rifle, optic, and cartridge combination. Even differences such as the scope you have mounted on your particular rifle will change the MPBR and subsequent zero. Find the manufacturers information on your favorite rifle load, google up a ballistics calculator, and in just a few minutes after plugging in your data you’ll have a good MPBR zero for your setup.

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Comments (36)

  1. Hello everyone. I am a bullet. I am very please with some of you for understanding how I behave, and very disappointed with those of you who have used me and my friends for decades and still don’t understand us. I am not a magical device, I do not have wings or flaps or ailerons. I am just a missile. Where I impact a target is more a matter of your perspective (line of sight) than magic rotational effects. I do not rise up in flight to hit people in the balls as Tj suggested. Most rifles are set up to launch me slightly upward so you can use to me to hit things that are further away. When you throw a baseball (good buddy of mine) from center field to home plate do you throw it in a straight line or do you lob it up slightly to get more range out of your throw? I know this is hard for some of you to understand but trust me, this is what I was born to do. I am a simple guy, and I’ll only fly where you tell me to fly, I do not have a built in computer or magical powers to rise on my own, but if you point your barrel up a little in relation to your sights, you will get a lot more use out of me.

  2. Some of you people arguing about bullet “rise” are arguing semantics. It’s a matter of perspective, as some have pointed out. For practical shooting, a bullet cannot rise above it’s bore-sight line. In flight, however, it’s trajectory does rise above it’s target-sight line.

    Some of you are arguing that various forces can cause a bullet to literally “rise” above it’s bore-sight line. It can, but keep in mind that they can also cause it to “dive” in different conditions. Furthermore, I doubt that anyone on this board have the expertise or skill level required to discern the slight difference it would make. That includes the military guys, unless you are a trained sniper.

    KISS. Bullet don’t “rise”, they are deliberately lobbed above the line of sight. No one who is still trying to understand this shooting 101 concept needs to be confused by spin-effects that won’t affect their early learning curve. And I have to agree–the illustration by the OP sucks.

  3. This conversation is just killing me! I was in Basic in October 1979, being forced to do what seemed liked countless pushups, flutterkicks, and several other excercises I can’t even remember.

    The reason for the abuse?

    I questioned the Basic Rifle Marksmanship instructor on this exact thing! Although I did a boatload of “remedial” exercises that afternoon, I never changed my argument.

    I did score expert during the qualification phase, and expert every time after that, for 24 years.

    Discounting a very small amount of spin induced lift, gravitational anomalies, and possibly weather related input; a bullet will not rise of it’s own accord. Period. The round does rise when leaving the muzzle, but only because the barrel is pointed at an upwards angle relative to the sight plane.

    For you doubters, try this next time you’re at the range….. get a good tight group shooting the way you normally do. Then, cant your rifle 90 degrees to the right or left and shoot another tight group using the exact same point of aim. Anyone want to bet me a beer that the second group is NOT going to be in the same place?

    Here’s another cool little experiment…. Put a rifle in a clamp with the barrel exactly two feet high and exactly perpendicular (level) to the ground. (Don’t worry about the sights, they are irrelavant for this experiment)
    Suspend a bullet at the same exact height as the muzzle. Figure out a way to release the bullet at the exact same instant that a bullet fired from the rifle leaves the muzzle.

    Which bullet will hit the ground first?

  4. The bullet never rises above the straight line projected by the bore site. But because the barrel is not level with the ground but angled upward relative to the line of sight, the bullet rises IN RELATION TO THE GROUND ONLY before arcing back to earth.

    A bullet fired from a horizontal barrel immediately drops to earth never rising above the bore axis. In no case, ever, will a bullet rise above the axis of the bore after leaving the muzzle. Period. But it can rise IN RELATION TO THE GROUND if the bore is angled upward. Such is the case with a battle rifle with a 300 yard zero.

    The over simplified example in the Marine manual is horribly worded and the illustration is even worse leading to this widespread misconception.

  5. The Gunnery Sergeant in Full Metal Jacket was a real Marine. Do you think he made up all of those insults on his own or were they a cumulation of excerpts from his growing up in the Corp. I am retired Army SF and my use of swearing was dependent upon target audience and the emphasis I wished to impose…a verbal METT if you will. Now we have a military where Affirmative Action Figures are more cherished than warriors as the Ultimate AAF has converted the military more into a Camouflage Welfare System and Social Experiment than even the Clintons. Of course we would never put these same ridiculous standards on our professional sports teams because winning is everything when it comes to accumulating trophies on an annual basis versus maintaining U.S. economic and military superiority. So without swearing I have agreed with Frank to explain how some people just don’t get the point with politeness because they make their half-assed opinions their religion. For the moron who stated that bullets don’t rise, just put your science to the test by vising in a rifle zeroed at 300 yards on a target 24″ high and the straddle the line of sight at 100 yards. At a minimum he won’t procreate the race anymore and this planet will indeed be a better place.

  6. “What does change is the trajectory of the individual bullet/cartridge.”

    PK,
    What exactly do you think trajectory means? It’s the curve of an object in flight, otherwise known as the RISE and FALL of an object.

  7. This post is to congradulate Nick in post 24 for correctly answering the original discussion from the rude and always right post from paul ( post 10 ) haha. Though i believe he is right when he says that the trajectory will not rise above the angle that it is fired from because of gravity, he will not understand until someone explains that there are two angles to consider. First the angle of the line of sight from which you are aiming via iron sights or scope, and the angle of the barrel itself. for example lets say you start off with a rifle that has its sights perfectly aligned with the barrel and you try to hit a target say at 400m. Most likely you will hit low so what do you do ?… you adjust the rear sights which actually raises the rear sight in elevation. This naturaly makes the shooter bring up the front sights a little to realign the sights. Now the barrel is angled up in reference to the angle of the iron sights/scope. The angle of your sights and or your view when aiming will be 0° in reference to the target because this is what your doing when aligning your iron sights with target; but now your barrel is angled up slightly. Now you may hit your 400m target with the arc of the trajectory allowing for further distance. I have never been in the military, but now am thinking that i should have signed up just to teach some of these hard headed leathernecks a thing or two about the first thing you should learn as a leatherneck…joking. I am sure the Magnus effect is real, but to the discussion of trajectory rise, it is im sure just a small part of the causes of trajectory rise. no need for formulas fellas, just a minor backround in shooting tin cans and jack rabbits ; )

  8. Chiming in on what was stated by Tom in post 17, follow this link for a better explanation http://m14forum.com/m16-ar15/29561-adjusting-your-iron-sights.html If not, in short, we (as in Marines) set our sites for 300 yards. The sites will angle the rifle upwards because of gravity pulling the round down. Even though you feel as if the rifle is level, it in fact is not. So you are slightly angling the rifle up, through trajectory, the round crosses the same elevation at 36 yards and at 300 yards. If you really want to try it out, go sight in at 36 yards. Then go set up some new targets at 36, 150, and 300 yards all in line with their dead center bulls eyes being at the exact same elevation, including the tip of your barrel after being mounted in a vice and aimed for the 36 yard target (now this is for the M16). If you don’t know how to make them all the same elevation, go to home depot or lowes and buy and learn how to use an auto rotary laser level. Before pulling the trigger, get a precision level and see how far your barrel is aiming upwards, thus showing you that the round goes up because you are pointing the rifle up, but aiming your sights level. If this were to be setup precisely with no distractions to the round while carrying the 300 yard length, you would have a hole at the 36 target and 300 target to be fairly fairly close to the exact same elevation while the 150 yard target would be much higher.

    Maybe I’m stating the obvious for some, but I know that what else I was taught in this great gun club I am proud to be a part of, is that sometimes you just have to make it Barney style for some.

  9. Even though this post is old and although some have posted since it’s beginning, I had to say something. First, PK posted on April 30, 2010 that a “bullet NEVER rises once it leaves the muzzle of any firearm.” I can’t tell if he is joking or if he is that damn stupid. It is evident he has never been in any of the Combat Arms MOSs (if he was even in the military). A simple search on the internet under “ballistics” would have ended that noise. Second, Tom rebuked Frank for his foul mouth, which was appropriate. “Political Correctness”? shoot, that’s only common decency. Frank should have learned that at home. I am Old Army, here is a quote for thought: “Swearing and verbal filth is not the mark of a soldier (or Marine?). It is a poor crutch for a man with a small vocabulary and in most cases, little intelligence.” That was a direct quote from Pamphlet 21-13, Department of the Army September 1964). I’d hate to think the USMC would disagree.

  10. brad, the jetboat and car are both curved on one side and (relatively) flat on the other. the same principle you describe states basically that if the air on one side of an object is moving faster than the air on the other side of an object, it will create lift. the bullet trajectory is not affect by this as the projectile is of uniform shape (in theory) so that the air is traveling a close enough speed on all sides to not create lift. at least this is my understanding, its been about 12 years since ive taken a physics course.

  11. a bullet will rise with enough force pushing it foward thats why jet boats or cars going fast enough will fly if going fast enough

  12. You must be a new school Marine. I am old school. First: F@#k your political correctness. Which, Is becoming a major downfall of our country. Read Thomas Sowell. Second of all: I never made a claim as to why a bullet rises, I just said that it does rise. So, why were you trying to school me and also tell me to go relearn. How about you relearn this: F@#k you.

  13. First of frank, it is very unbecoming of a Marine to speak as such while representing the Marine Corps I know in the infantry I would make sure you’d never make that mistake. Although this is an old post I had to comment. It is the angle of the rifle when the rear sight is elevated(or scope) that would make it seem as if the bullet would have an upward trajectory. your simply angleing the rifle up, and for what you ask? Well to componsate for the fall of the bullet as it looses speed and atmospheric pressure takes more and moreeffect on pushing the bullet down. Now I am sure they teach this in boot frank so maybe you should go back and re learn it, and hey while your there go ahead and pick up some common sense, and then defiinantly study up on your Corps values and learn to embrace them. And for everyone else I applogize for this Marine, and next time your sighting in down range take a second and look at how your holding the rifle and it will make sense.

    Semper FI

  14. Happy Clock Owner: I am a Marine and you are a f@#king douch bag. Bullets rise. Learn to read and find out why a bullet does rise.

  15. The commenters are all correct, in their own frame of reference.

    The illustration is confusing (and pretty lame, to be that confusing – I blame the art department.)

    If the illustration showed the rifle angled so that the barrel pointed along the initial bullet trajectory, this argument would all go away. The sight line should be shown as level, not the gun. Of course, the angle between line of sight and bullet trajectory would need to be exaggerated in order to show up in an illustration this small.

  16. Once again referring us to Wikipedia is not an effective argument. Yes, the Magnus Effect probably has some effect on a bullet in flight. If you were shooting a thousand yards in a stiff cross-wind, you might miss by 1/4″ from the Magnus Effect and 4 feet from wind-induced drift.

    Mentioning the Magnus Effect in the present discussion about ranges where you are relying on a couple of inches of gravity-induced drop to be close enough to kill a man (or a moose) DRT is just plain silly. If you can’t comprehend that a bullet goes up, then down, when firing at a target at the same elevation as the shooter, you have missed more than just the finer points of long range shooting arts.

  17. Oh for f@#k’s sake: http://en.wikipedia.org/wiki/External_ballistics

    Read the part about the Magnus effect. This is why most military arms have a left hand twist to the rifling. It actually DOES cause the bullet to rise (though in my opinion at the cost of increasing spin drift, just a personal observation).

    The magnitude of the effect of each of these forces is up for debate depending on the EXACT place (as in latitude and longitude), distance and elevation to target, air pressure, air density, humidity, and trajectory of the shot.

    There is a reason that “sniper” is an entire job in the service, not just an additional duty (like Designated Marksman).

  18. Paul,

    Your second post is correct. The ball’s trajectory will never rise above the angle at which it is thrown; nor will the bullet’s trajectory. That’s why the bullet is launched—like a ball is thrown— at an upward angle. Like a ball, it is this angle, not angular momentum, which causes it to rise.

    I apologize, for I seem to have misunderstood your original comment.

    — John.

  19. When I launch a ball, even at an upward angle the flight of the ball will never rise about the plane of the angle thrown. If the object cannot rise above the palne of the angle imparted to its fligh how can a bullet rise above the plane of the angle. Or have angles become curves in this universe of which you speak?

    BTW, I don’t impart much weight to a publicly edited encyclopedia.

    But this will degrade in to a P…..g match, so you sight in your guns your way and I will soldier on with my imperfect understanding of this universe.

  20. @Paul:

    Actually, a bullet rises not from angular rotation, but for the same reason that a ball rises in the air when you toss it to someone 20ft away: it is launched with an upward angle. Those of us who Remember physics 101 (and in my case, teach Calculus 101, which uses physics problems as examples) remember a formula like h = v_0 t – 1/2 at^2, where v_0 is the initial (upward) velocity, a is the acceleration due to gravity (e.g. 9.8m/s^2, or 32ft/s^2) and t is the time since launch.

    (Of course, this formula discounts the effects of air resistance, which in our case is not a very bad assumption since the *vertical* velocity of the bullet is so small, while its *horizontal* velocity is quite large. In fact, that 55gr 5.56mm with its muzzle velocity of around 3200ft/s has an initial vertical velocity in the neighborhood of 6.5ft/sec.)

    When your sights are aligned perfectly horizontally, the barrel of your firearm is canted very slightly up, to impart an initial upward velocity. Yes, gravity does have an immediate effect, which is not (as in the example of the baseball) to make it fall as soon as it leave the barrel, but to *decrease* its upward velocity. Since the barrel is only slightly canted, it doesn’t take long (i.e. time) for the bullet to lose this vector and start falling.

    This is also why there are TWO intersections to your zero: the bore ends below the plane of your sights, but because of that cant, the bullet is traveling upwards, through that plane and beyond, where it begins to fall back down through the plane of your sights.

    If your barrel was aligned perfectly horizontally, then yes, the bullet would drop immediately. If that were always the case, then it would be impossible to hit a target at the same elevation.

    If you’d like a more detailed reading, try http://en.wikipedia.org/wiki/External_ballistics. Or try Physics 101, but this time stay awake the whole time.

  21. You guys must have slept throught physics 101. yes, both gravity and friction act on a bullet and will cause it to fall, which is why a bullet drops. At the beginning some anglular rotation is imparted on the bullet that causes it to rise in the early part of its flight.

    As the forces of gravity and friction slow the bullet down the anglular forces lessen.

    simple physics. Learn them or they will cause regret.

  22. If you point a gun in the air and pull the trigger, does the bullet fall straight to the ground? No. Gravity DOES start taking effect immediately. The barrel of the M16 (and probably MOST rifles) is pointed at an upward angle, so yes the bullet WILL rise initially.

    7 yrs USMC. 3rd award Expert

  23. If the bullet never rose, it would never hit the point of aim. This is because the scope/sighting device and the rifle bore are not coincident. As you know, traditionally the sighting device is 1″ – 2.5″ above the bore. Since the bullet DOES start dropping immediately, the bore is actually pointed slightly upward relative to the line of aim. So the bullet goes up, levels off, and starts down. So, depending on the target’s location, it can cross the line of sight twice.

  24. A bullet doesn’t rise? What planet are you on? You might want to contact the United States Marine Corps and let them know that “a bullet never rises” as they feel differently.

    When the sight angle between the bore and the scope is set correctly, the bullet will RISE until it reaches the apex of its trajectory, crossing through the line of sight once on the way up and once on the way down.

  25. Get real. A bullet NEVER rises once it leaves the muzzle of any firearm. Gravity takes effect immediately on exit from the bore. This zero technique is based on the fact that the bore and sight line (whether scope or iron sites) intersect downrange. The type of scope used is irrelevant so long as the distance between the center of the bore and center of the scope lens is constant. What does change is the trajectory of the individual bullet/cartridge. The basic technique is valid for any firearm/site combination so long as the trajectory of the round being used is known. Standard ballistic table provide that information.

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