Just got my first AR-15. Reading the ballistic charts says If I want to zero for 100 yards and my range is only 25 yards, I need to set the hits to about 1.5" below bulls eye. Did I read it correctly?
BTW, I'll be using .223 55 grain FMJ.
Bigham
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I don't have that chart, but yes, that conclusion sounds completely logical. A 100 yard zeroed rifle would be low at 25 yards.
However, 100 yards is a poor zero for that round. Instead of having 2 passes on the aiming line it basically barely kisses it right at 100 yards, leading to a greatly shortened maximum point blank range compared to what the round is actually capable of. A 50 yard zero works much better. Google the differences between a 50 yard zero and a 100 yard zero for .223. It's a pretty massive difference, way better zero for the round.
Staap It
LOL, Just answered a like question the other day. What you speak of is called a "near zero". Near Zero because of the short 25 yard distance, AND near zeroed because it may be close to being zeroed. You MUST fire the range you want to zero to. Zero IS a PRECISE adjustment. Close is NOT zeroed.
This entire premise makes use of a known "point blank" range performance. Near zero can provide a bullet strike often within 2" high or low, in most likely the vertical plane. You can set the sights at least to battle rifle precision, but, if you want a real zeroed set of sights, you have to shoot the distance ACTUALLY where you want to be zeroed.
If this was an M1 Garand I could tell you exactly where to set your sights and be near zeroed with out firing a shot at 200 yards.
Added : Please excuse my avoidance of absolutes. From experience I know things often are different then expected, so I avoid saying this is always the case, because that would definitely be a mistake. Full disclosure.....
John de Witt
If the sights on your AR are high on the handle, then you'd expect that close-in shots are going to be low. Perhaps even lower than that. At any rate, you can't zero your rifle on a 25 yard range. All you can hope to do is get "on paper" so you can zero when a real firing range becomes available to you. You just can't do it until you do it. Your load, your rifle. No generic chart is going to be much help.
Anonymous
You might be in the ballpark doing it that way. But why not go to a 100 yard range and sight it in like everyone else does? If I remember correctly, you live in Texas. You should be able to find a 100 yard range fairly close by. Getting it right is worth a little extra effort.
Space Cowboy
If that's what it says... I recently sighted my 308 in @ 25 yards...and according to the supplied Hornady data, it should be zeroed for 200 yards. It will hit an inch...inch and a half higher, at 100...(if I remember...don't have the box, anymore.)