FNFiveSeven
Member
- Joined
- Jan 3, 2003
- Messages
- 538
Hey all,
Yesterday (and part of today) I decided to sit down and write a small "basic" program that allows you use your calculator (assuming it can be programmed, e.g. my Ti-82) to tell you how much elevation you need to hit your target based on its distance AND inclination/declination from the shooter. I used a cubic fit for the trajectory data (from Sierra) to provide the equations so that you have a continuous "drop" curve, i.e. you can figure out how much drop there is at in-between distances, like 772 yards. I made the program compatible in both metric and english measuring systems and it outputs the answer in both inches,MOA and cm,cm/100m you can use both American and Euro optics. The best part of this program is that it uses Sierra ultra-awesome formula for figuring out how to shoot at elevated/declinated targets, and this program should predict the strike of the bullet to less than 2 inches at all ranges and all angles up to 1000m. Less than 2 inches of error is pretty good at a km considering the error in the rifle will be far, far greater anyway. The parameters for the cubic equations will only work perfectly if you are shooting a 168 grain .308 match bullet out of a 24"bbl, with a scope mounted about 1.5" above the centerline of the bore, and assuming that you are shooting within a couple thousand feet of sea-level. If you want to tune the program to your load, you'll have to re-compute the parameters by doing cubic regression on the data corresponding to your load, which you can usually get from Sierra or whomever... but the rest of the program should still work just fine. Oh yeah, FYI the parameter "D" is absolute bullet drop, i.e. it's always negative at any distance from the muzzle, regardless of what range the rifle is zeroed at. The parameter "I" is the drop of the bullet (in inches) relative to the crosshairs, assuming a 100 yard zero. Good luck and let me know what you think and/or if you have any suggestions. With this program, all you have to do is attach an angle-cosine inclinometer to your rifle, and keep a programmable calculator and laser rangefinder in your rifle case, and you're ready to go shooting beyond 1km up a 45 degree hill.
-Robert
:ClrHome
:Menu("RANGE UNITS","YARDS",1,"METERS",2)
:Lbl 1
:Input "YARDS=?",Y
:Goto 3
:Lbl 2
:Input "METERS=?",M
:M*1.094 --> Y
:Lbl 3
:-3.350352E-7Y^3 - 5.895526E-5Y^2 - 0.0049468159Y + 1.246485221 --> I
:-3.34995E-7Y^3 - 5.901716E-5Y^2 - 0.0483006822Y + 2.994635349 --> D
:Menu("SLOPE CORRECTION","IGNORE",4,"cos @",5,"@",6)
:Lbl 4
:1--> C
:Goto 7
:Lbl 5
:Input "cos @=?",C
:Goto 7
:Lbl 6
:Input "@=?",A
:cos A --> C
:Lbl 7
:-D(1-C)+I --> P
*2.54 --> Q
:ClrHome
P*95.492966/Y) --> K
:Output(1,1,round(K,2))
:Output(1,9,"MOA")
:Output(3,1,round(P,2))
:Output(3,9,"INCHES")
:Q*(100/(Y/1.094)) --> L
:Output(6,1,round(L,2))
:Output(6,9,"CM/100M")
:Output(8,1,round(Q,1))
:Output(8,9,"CM")
:Stop
Yesterday (and part of today) I decided to sit down and write a small "basic" program that allows you use your calculator (assuming it can be programmed, e.g. my Ti-82) to tell you how much elevation you need to hit your target based on its distance AND inclination/declination from the shooter. I used a cubic fit for the trajectory data (from Sierra) to provide the equations so that you have a continuous "drop" curve, i.e. you can figure out how much drop there is at in-between distances, like 772 yards. I made the program compatible in both metric and english measuring systems and it outputs the answer in both inches,MOA and cm,cm/100m you can use both American and Euro optics. The best part of this program is that it uses Sierra ultra-awesome formula for figuring out how to shoot at elevated/declinated targets, and this program should predict the strike of the bullet to less than 2 inches at all ranges and all angles up to 1000m. Less than 2 inches of error is pretty good at a km considering the error in the rifle will be far, far greater anyway. The parameters for the cubic equations will only work perfectly if you are shooting a 168 grain .308 match bullet out of a 24"bbl, with a scope mounted about 1.5" above the centerline of the bore, and assuming that you are shooting within a couple thousand feet of sea-level. If you want to tune the program to your load, you'll have to re-compute the parameters by doing cubic regression on the data corresponding to your load, which you can usually get from Sierra or whomever... but the rest of the program should still work just fine. Oh yeah, FYI the parameter "D" is absolute bullet drop, i.e. it's always negative at any distance from the muzzle, regardless of what range the rifle is zeroed at. The parameter "I" is the drop of the bullet (in inches) relative to the crosshairs, assuming a 100 yard zero. Good luck and let me know what you think and/or if you have any suggestions. With this program, all you have to do is attach an angle-cosine inclinometer to your rifle, and keep a programmable calculator and laser rangefinder in your rifle case, and you're ready to go shooting beyond 1km up a 45 degree hill.
-Robert
:ClrHome
:Menu("RANGE UNITS","YARDS",1,"METERS",2)
:Lbl 1
:Input "YARDS=?",Y
:Goto 3
:Lbl 2
:Input "METERS=?",M
:M*1.094 --> Y
:Lbl 3
:-3.350352E-7Y^3 - 5.895526E-5Y^2 - 0.0049468159Y + 1.246485221 --> I
:-3.34995E-7Y^3 - 5.901716E-5Y^2 - 0.0483006822Y + 2.994635349 --> D
:Menu("SLOPE CORRECTION","IGNORE",4,"cos @",5,"@",6)
:Lbl 4
:1--> C
:Goto 7
:Lbl 5
:Input "cos @=?",C
:Goto 7
:Lbl 6
:Input "@=?",A
:cos A --> C
:Lbl 7
:-D(1-C)+I --> P
*2.54 --> Q:ClrHome
P*95.492966/Y) --> K:Output(1,1,round(K,2))
:Output(1,9,"MOA")
:Output(3,1,round(P,2))
:Output(3,9,"INCHES")
:Q*(100/(Y/1.094)) --> L
:Output(6,1,round(L,2))
:Output(6,9,"CM/100M")
:Output(8,1,round(Q,1))
:Output(8,9,"CM")
:Stop
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