This brings up a pet peeve of mine. All ballistics programs will tell you what you drop is at some point if your zero is 100yds or some specified distance. What I wanted is to know is where to set my sights so that my bullet will never be more than a specified distance above the line of sight and the max distance at which it drops below the specified distance. In other words, how should I sight my rifle so that the bullet will never be more than say 3 inches above the target and the range at which it will drop 3 inches below the target.

The 270 bullet in the original question will be almost 4 inches high at about 160 yards. This may, or may not be acceptible, but is generally hidden when looking at ballistic tables.

If you are interested, I wrote a program to do this. Send me an e-mail and I'll mail you a CD.

Robin

bailes @ gci.net
[image]http://us.f2.yahoofs.com/users/41c380d8z8615f6bc/7ed0/__sr_/91e6.jpg?phoa4wBBUB7nqSi1[/image]

I was hoping this would show an image. All this computer stuff is way too complicated...

http://us.f2.yahoofs.com/users/41c380d8z8615f6bc/7ed0/__sr_/91e6.jpg?phoa4wBBUB7nqSi1

Why not simply go to http://stevespages.com/page8b.htm and download a copy of all the ballistic programs you want?

Your looking for your "point blank range"?

using the data CC gave above, with standard atmospherics and a sight height of 1.5"

+2.45" @ 100 = +3 at 152yd (max height), zero at 268yd, -3 at 315yd, -11.4" at 400yd and -27" at 500 (or -5.2MOA) and 2244fps remaining velocity

CC, Here's a pretty good program thats alot of fun to fool around with.

http://www.norma.cc/htm_files/javapagee.htm

RobinB,
Shooting Lab has that option "Max Point Blank Range" You insert your vital dimensions (6" for the following) and it will tell you what yardage to sight in at for max PB range.

Jim
MaxPB

RobinB,
Shooting Lab has that option "Max Point Blank Range" You insert your vital dimensions (6" for the following) and it will tell you what yardage to sight in at for max PB range.

Jim

Hey jim, or anyone else for that matter, I plugged in the 3200 fps .447 BC and came up with 315-320 yards MPBR depending on what I set the elevation above sea lever to be with the point blank program. I know this aint a lot but why such a big difference in calcluations and which program has the right info

CC

Air density, the higher you are the thinner the air is. Temperature, humidity and barametric pressure will also affect the curve for the same reason.

The denser the medium, the larger the drag on the bullet (effectivly lowering the BC) & the shorter the MPBR will be. The reverse is also true, the thinner the medium the longer the MPBR will be.

You have also just stumbled onto one of the main reasons that the "long range" guys always state that you must test fire your rifle/ammo combo at long range to verify/correct the generated drop charts.

All of the programs are basicly correct, the biggest differences come from the increment used between calculation points, and how far out they carry the numbers before rounding/truncating. IE: One program may re-calculate velocity every foot, while a second might do it every 30feet. One may go 2 places past the decimal, one may go 10 places. The shorter the distance between calculations the more accurate the result, the more places after the decmal before rounding/truncating the more accurate. I'm speaking of the internal numbers, not the displayed results.