Gaiudo

September 13, 2007, 01:39 AM

Trying to figure out the least common denominator for determining trajectory... is it possible to find a certain trajectory with:

a) Knowing only the first couple hundred yards of a certain cartridge's trajectory, is it possible to know exactly the remainder of its flight path?

Say one knows that a particular round, sighted in at 100 yards with a muzzle velocity of 2800fps, will be -3.8 inches at 200 yards, and -13.9 inches at 300 yards. Is it possible, with only this information, to calculate the remaining trajectory data out to the end of its range?

or else:

b) If not, how many more variables do we need to add before calculating the remaining trajectory. Would knowing that the above bullet were a 150 grain .308, would that be enough? Or would we actually have to know the particular bullet composition (e.g., Nosler boattail), the BC, etc.?

I'm working through learning the ins and outs of reloading and bullet trajectory, and am trying to figure out how much needs to be known before a ballistic chart can be calculated.

Thanks,

Nick

Edited to ask one more question: On an online ballistic sheet I printed out (not particularly related to any cartridge combination I would use), it lists six categories: Range, Velocity, Impact, Drop, ToF, Energy, Drift. The first two, and the last two, are fairly obvious.

However, I don't know what ToF indicates. Secondly, I'm not really sure of the difference between Impact and Drop. At 0 yards, it shows -0.75 impact, while it shows 0 drop. At 200 yards, it shows -4.31 impact, while it shows 10.14 drop. For 525 yards, it -62.16, and 78.69 for impact and drop, respectively. For my use, lets say I range a target at 525 yards. Should I come up 10 MOA (for 62.16 inches impact variation), or should I come up aprox. 13.3 MOA (for 80 inches drop)?

Thanks, this is all new, but very interesting and helpful.

a) Knowing only the first couple hundred yards of a certain cartridge's trajectory, is it possible to know exactly the remainder of its flight path?

Say one knows that a particular round, sighted in at 100 yards with a muzzle velocity of 2800fps, will be -3.8 inches at 200 yards, and -13.9 inches at 300 yards. Is it possible, with only this information, to calculate the remaining trajectory data out to the end of its range?

or else:

b) If not, how many more variables do we need to add before calculating the remaining trajectory. Would knowing that the above bullet were a 150 grain .308, would that be enough? Or would we actually have to know the particular bullet composition (e.g., Nosler boattail), the BC, etc.?

I'm working through learning the ins and outs of reloading and bullet trajectory, and am trying to figure out how much needs to be known before a ballistic chart can be calculated.

Thanks,

Nick

Edited to ask one more question: On an online ballistic sheet I printed out (not particularly related to any cartridge combination I would use), it lists six categories: Range, Velocity, Impact, Drop, ToF, Energy, Drift. The first two, and the last two, are fairly obvious.

However, I don't know what ToF indicates. Secondly, I'm not really sure of the difference between Impact and Drop. At 0 yards, it shows -0.75 impact, while it shows 0 drop. At 200 yards, it shows -4.31 impact, while it shows 10.14 drop. For 525 yards, it -62.16, and 78.69 for impact and drop, respectively. For my use, lets say I range a target at 525 yards. Should I come up 10 MOA (for 62.16 inches impact variation), or should I come up aprox. 13.3 MOA (for 80 inches drop)?

Thanks, this is all new, but very interesting and helpful.