Importance of T.O.F.???

[shortpants]

Now that you guys have shown me the light I agree that there is little use for TOF so if your asking me to explain anything to you I can barely tie my shoes!

 

[Michael Eichele]

The problem is the above assumption is incorrect. A high BC bullet starting slower will drift in the wind less than a low BC bullet if their time of flight is identical.

Think of the phrase "affected by environmental parameters" you used above. The best measure of that is how much velocity is lost on the way to the target, not the average velocity to the target. In the case above, both bullets average the same velocity to the target. The low BC bullet starts faster, ends slower which means it lost more velocity along the way. This means it was more "affected by the environment" than the high BC bullet. If the air slowed the bullet down more, it also pushed it sideways farther.

So as you can see, as far as wind drift is concerned, BC is a much more important value than TOF for any given distance. For drop, yes, TOF is what matters. But that's easy.

I just want to reinforce what Jon A has stated here. He is absolutely correct.

My take on why we dont pay much attention to TOF here and why manufacturers dont use it as a marketing ploy is because TOF does not tell you much in regards to retained energy, wind drift, or trajectory even though a very short TOF and flat trajectory go hand in hand it wont give you a clue as to what the remaining energy or windage or lack thereof will be. Short TOF does not mean high retained energy or small amounts of drift.

When a manufacturer tells you the BC is .550, you can guage how the windage values and retained energy are going to compare against a load that sports a .500 or .600 BC regardless of TOF. The bottom line is the numbers that ARE important to longrange hunters are retained energy, retained velocity for expansion and minimal wind drift for forgivness. TOF does nothing to tell us these numbers.

Also, TOF in and of itself does not give you even a close idea of how bad the drift will be. The 'lag' time WITHIN the TOF will determine how much or little a bullet will drift. That is why Lazzeronies 308 warbird using 168's at 3600 FPS have more drift and less energy than my 308 running 208 AMAX's at 1000 yards. The 168 at 3600FPS TOF is roughly 1.2300 and mine is 1.5558 seconds. The 168 is clearly much more impressive on the surface but in reality it means very little, in fact the important numbers are just not as good despite looking better.
Clear as mud right??

M

 

[eddybo]

Gotcha......somedays I have to wear the kind of shoes with velcro

Now that you guys have shown me the light I agree that there is little use for TOF so if your asking me to explain anything to you I can barely tie my shoes!

 

[RockyMtnMT]

I just want to reinforce what Jon A has stated here. He is absolutely correct.

My take on why we dont pay much attention to TOF here and why manufacturers dont use it as a marketing ploy is because TOF does not tell you much in regards to retained energy, wind drift, or trajectory even though a very short TOF and flat trajectory go hand in hand it wont give you a clue as to what the remaining energy or windage or lack thereof will be. Short TOF does not mean high retained energy or small amounts of drift.

When a manufacturer tells you the BC is .550, you can guage how the windage values and retained energy are going to compare against a load that sports a .500 or .600 BC regardless of TOF. The bottom line is the numbers that ARE important to longrange hunters are retained energy, retained velocity for expansion and minimal wind drift for forgivness. TOF does nothing to tell us these numbers.

Also, TOF in and of itself does not give you even a close idea of how bad the drift will be. The 'lag' time WITHIN the TOF will determine how much or little a bullet will drift. That is why Lazzeronies 308 warbird using 168's at 3600 FPS have more drift and less energy than my 308 running 208 AMAX's at 1000 yards. The 168 at 3600FPS TOF is roughly 1.2300 and mine is 1.5558 seconds. The 168 is clearly much more impressive on the surface but in reality it means very little, in fact the important numbers are just not as good despite looking better.
Clear as mud right??

M

That is right on. As a shooter you need to figure out what range a given projectile is going to be used. Plot out the trajectories of the projectiles that are in question. At some point down range the slower higher bc projectile will surpass the faster lower bc bullet for drift and often drop. At what point down range that happens is what the user needs to know in order to make an informed decision as to which bullet to use. The ratio of speed and bc of each bullet will change at what point the higher bc bullet will out perform the lower bc bullet.

I hope that makes sense.

Steve

 

[dustybrown]

The article about "Whats wrong with .30 cal ? Is a good read... seemed to be a good example here..."Muzzle velocity is a depreciating asset, not unlike a new car, but BC, like diamonds, is forever." Salazar...
It helped me wrap my mind around the topic.
This is great stuff.... food for thought.
Thanx