What does "point blank range" mean?

That goes back to the daze before scope sights, of course. It means that distance at which no hold-over is necessary to hit a target. In the era of smoothbore muskets, with their loose-fitting round-ball projectiles, it also meant that distance at which there was no doubt of hitting a man. Given the erratic nature of a "group" from such muskets, that was pretty close.

How those particular words came into use? I don't know.

Nowadays, for the majority of center-fire rifles, it's around 300 yards for deer-hunters. The key is the flatness of the trajectory.

FWIW, Art
 
A more "technical" reply might be: "the range for which the maximum ordinate of the projectile does not rise above the danger space (or beaten zone, or vital zone of the target)."

In other words, as a bullet leaves the muzzle, it rises relative to the line of sight, because the barrel of the rifle is pointed slightly upwards and the sights or scope are higher than the muzzle. At some point, the bullet crosses the line of sight and continues to rise as it goes downrange. The point at which it "climbs" the highest is the maximum ordinate. It then drops as the bullet continues downrange, once again crossing the line of sight and continuing to drop as it heads downrange. At another point, it has dropped below the line of sight an amount equal to the maximum ordinate. This distance downrange is the point blank range.

Huh? OK, it just means the distance over which your bullet doesn't drop or rise more than an assumed # of inches (such as 4") above or below the line of sight.

By checking ballistics tables and adjusting your sight/scope, you can set the maximum ordinate to be no more than one-half of the size of the vital zone of your target. For example, you can just sight your .30-06 to hit 2" - 2 1/2" high at 100 and you have a point blank range of about 250 yards (assuming a target with a vital zone of 8"). Military rifles are set up so that the assumed vital zone is bigger and therefore the assumed PBR is longer. They tend to be zeroed for 300 yards. Of course, this means that at very close range, your bullet's likely to sail over the heads of the badguys if you don't apply a little KY windage.

Then, as Art points out it means that distance at which no hold-over is necessary to hit a target.
 
Shin-Tao is on the right track. The term comes from a gunners' quadrant, used in the old days to determine the elevation of a cannon. The quadrant was like a carpenters' square with a 90 degree arc inside it. A plumb bob was hung from the point of the angle. The long arm was placed in the barrel and the cannon elevated until the bob reached the point on the arc marked with the desired range setting. The point at which the cannon bore was level had no marking, so it was the blank point, or "point blanc" in French. Since French military techniques, terminiology, and equipment were very influential on both European and American armies, the term came to be used in all armies for a range at which no elevation was needed.

Jim
 
The manual that came with one of my scopes, has "point blank range" defined as the area of the bullet's path before it crosses the line of sight on the upward portion of it's path.
Eric
 
without beating up on Webster or delving into history....for the common man with a rifle it means:

if a rifle with the sights set up for the maximum point blank range you are able to aim at the center of a "kill zone" on a game animal and shoot. if everything is set up right you will not have to aim low close up or holdover at extreme distance. as long as the game is within the point blank range you will hit the kill zone.

on whitetail deer the average kill zone is thought of as being a circle 4 to 6 inches across centered in the deer's chest over the lungs.

most ballistic computers contain a function that will figure max point range if given sight distance above the bore, bullet weight, bullet ballistic coefficent, muzzle velocity and distance above sea level. barometric pressure and angle up or down hill also affect the formula but only to a lesser degree. the result of the formula will usually tell you how high to set your point of impact at 100 yards.

simply put for most modern rifles with hunting loads it comes out to 1.5 to 3 inches high at 100 yards. giving a max point blank range of from the high 200 yards to the low 300 yards.
 
What Riddle said is about right for us laymen, and exactly the opposite of what those D!ckhead newsmen mean when they say point blank. They mean muzzle pressed up against target. Morons! Sorry! <rant mode off>
 
Hey, Jim Keenan, Sir!

To pick a truly trivial nit, "blanc" in le Francaise means "white", non?

Of course, the absence of a dark-colored line on a light- or white-colored quadrant could be the "pointe blanc". (Absent a French-English dictionary, I think it's "pointe".)

I like your answer better than mine, anyway...

:), Art
 
Hi, Art,

I speak French perfectly after having spent two weeks in Quebec. If you believe that... Actually, French is not one of my languages, but my dictionary gives "point" and says that "blanc" can mean white or blank. Pictures of gunners' quadrants I have seen have no "zero" range marking, so I guess "blank" is as good as any.

FWIW, some while back I mentioned the gunners quadrant as being obsolete and was told that they were used at least up to WWII to adjust sights. I don't know how this was done, but it was interesting that such an old device was still in use that late.

Slightly off topic, but here is a thought. The army today has a laser range finder that is supposedly accurate to under 3 inches at 10 miles. Question: How in hell do they know, and how do they calibrate it? Thirty thousand GIs with yardsticks would never be that accurate.

Jim
 
GPS is almost accurate enough to test it. most laser survey equipment is VERY accurate at measuring distance. i remeber reading that NASA left a laser reflector mirror on the moon. with it they were able to measure the EXACT distance to the moon within a few feet.
 
Hi, riddleofsteel,

GPS is nowhere near that accurate, and no surveying equipmetn comes anywhere close. The moon distance can be off a lot and not matter. The question was not whether the range finder is accurate, but how could it ever really be proven.

Jim
 
Interesting stuff here guys. I learned something. :cool:

Please excuse me poking my nose in...

About GPS, it can actually be quite accurate. Starting from a known location (set by the USGS), you can use GPS to mark a new location and correct your lat/lon by correlating this new position with the known location. This is called differential GPS and the best equipment has proven to be accurate within 5 millimeters. And this was five years ago, I imagine that today's systems are even more accurate.

On laser range finders, they are calibrated using much smaller distances and the accuracy is extrapolated out to the longer distances. With modern test equipment, it's possible to calibrate these devices to within a single wavelength of light. Field equipment doesn't have to be that accurate (it probably can't be--not engineered for it), but the calibration accuracy is there if you need it. The "huge error" of three inches in ten miles is likely due to the limitations in the device itself, not its calibration.

Just thought I'd throw in...

Ken
 
If I understand what the boffins can do, measurements in nano-seconds can be made. Since the speed of light is known, and the length of time for a laser to "get there" and return can be measured, calculating distance is then simple math. The measurement of time is what takes esoteric equipment--and that's what Mr. Bushnell will sell ya.

A large, mobile laser rig is used to bounce signals off that reflector on the moon to measure fault movements. San Andreas, etc. It was, at one time, based at the MacDonald Observatory near Fort Davis, Texas; it was used at various fault-locations around the world. Haven't kept track, lately.

Art
 
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