Term for initial point at back side of trajectory?

[M4Fundi]

Term for initial point at back side of trajectory? On a 50/200 yard Zero the 50 yard point is called the initial point what is the point at 200 called?

[markm]

The pot of gold at the end of the rainbow? :p

Sorry... I don't know.

[RogerinTPA]

Term for initial point at back side of trajectory? On a 50/200 yard Zero the 50 yard point is called the initial point what is the point at 200 called?

Secondary impact point? Most refer to it as "Point of Aim/Point of Impact". A 50 yard zero should give you the same POA/POI, at 200 yards (actually 225 yards or there abouts). It's always a good idea to confirm your zero at the 200 yard distance to assure the degree of accuracy.

[M4Fundi]

Why would it be called POA/POI if it crosses (between 200-235) but you might be aiming at 300:confused:

[markm]

Why would it be called POA/POI if it crosses (between 200-235) but you might be aiming at 300:confused:

POA/POI are two specific distances for any given sight setting. If you do the 50 yard zero they're the two distances above.

If you're aiming at a 300 yard target, you'll know that your POI will be a little low compared to your 200 yard POI.

[RogerinTPA]

There are many kinds of aiming points that a shooter will use. The "Six o'clock" hold, where you put the front sight at the bottom of the target you want to shoot. It is also the most common and most often taught. "POA/POI" / "Center Mass" hold, where you place the front sight post right in the middle of the target, and "12 O'clock" hold where you place the front sight on the top of the target, completely covering it. All of these techniques work, regardless of shooting distance. POA/POI or center mass hold, is the easiest to teach to anyone not familiar with shooting and the most common and natural area, where anyone with no shooting experience, would aim.

Trajectory. A bullet launched will always have an arcing flight path. Some weapons have a greater arc or trajectory, than others. Some are flatter due to a higher velocity caliber being used. The greater the distance, the greater the arc. The amount of arc/trajectory, also depends on the distance in which the weapon was zeroed, as well as the type of round being used. This also includes artillery, where some pieces are referred to as "guns" due to shooting a flatter trajectory and the more traditional howitzers cannons, have a greater arcing trajectory. The 50/200 yard zero for the AR15, provides a convenient trajectory which provides a dual zero, whether the aiming point is a "Six O'clock hold", "POA/POI"/"Center Mass" hold, or "12 O'clock" hold, at 50 and 200 yards, with a max trajectory of approximately 2 to 3 inches, without a hold over, or raising your point of aim to compensate for shooting at a more distant target than the weapon was initially zeroed for. Any firearm will have several points of impact along it's trajectory, based on distance. There are several charts on on this forum that explain them in great detail.

There are also some folks who prefer a 25, 50/200 or 100 yard zero. Each one of those zeros has a completely different secondary impact point from the other. The 50/200 yard POA/POI, is the most efficient zero for engaging targets, without changing your point of aim or hold over, for most folks.

[M4Fundi]

I understand intimately everything said and greatly appreciate the efforts, but I do not think that they answer my question.

I understand the uses of 7, 25, 50, 100 yard Zeros, etc but on a 50/200 Zero (my preference) if your POA is at "any" distance past say "215" (where the bullet crosses the Line of Sight the second time) then the bullet will cross the line of sight at 50 and again at that "215" everytime even if your POA is say 350 or 436 or 294, etc., which would make your POA 350, 436 or 294 and not "215", so it would seem incorrect to label the second point at "215" the POA or POI if you are not aiming there and the bullet is not impacting there.

[Molon]

If I understand your question correctly; first crossing and second crossing or near zero and far zero.