BrentM
Well-Known Member
Well the longer a bullet is subjected to the force of wind the more it will be deflected. Taking into account bc is equal only tof really the only difference. That's what I did for the tof I posted above
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Long range hunting comes down to 2 separate things wind and flight time
- Thread starter Barbourcreek
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brant89
Well-Known Member
Then the lag times would be .095 and .097 respectively, but that is disregarding any rounding errors. They are probably actually much closer. This actually further illustrates that fact that it's lag time, and not TOF that determines wind drift. One bullet arrives .12 seconds later than the other, but drifts the same amount. Why? Because the lag time is essentially the same.
brant89
Well-Known Member
This is exactly what I'm trying to illustrate as being untrue. Above I've posted two examples of bullets that were subjected to crosswind for a longer period of time but resulted in less wind drift. TOF is NOT the deciding factor, it's lag time. We're those TOFs from a ballistic calculator for those specific bullets?
BrentM
Well-Known Member
17.1 vs 13.2 drift at same bc and 2800 vs 3300
brant89
Well-Known Member
So you are comparing the same bullet, but one at a higher velocity, which means the higher velocity one will have a lower Cd and a LOWER lag time. So yes, the TOF is shorter, but so is the lag time. The only way to illustrate the point is to use different bullets so that the TOF and lag time aren't proportionally related through BC.
BrentM
Well-Known Member
Correct. Where people can get overly confused is using a low bc bullet and high velocity or vice versa. Often a slower high bc bullet overall out performs a faster low bc. Just have to run the numbers and study the ballistics
brant89
Well-Known Member
Because people don't understand what "directly related" means in physics and mathematics. I've illustrated twice now with real numbers that you can have an increased TOF with decreased wind drift. That is NOT a direct relationship, and it's not an INVERSE relationship either. The fact of the matter is that they are ONLY related to one another when you add another variable which in this case is TOF in a vacuum, hence it IS directly related to lag time but NOT TOF.
LRNut
Well-Known Member
Litz has written extensively about lag and wind drift- just get his books.
Certainly impressive shooting, especially considering the world record 10 shot group (heavy gun) at 1000 yards is about 50% larger than the diameter of a golf ball.
I am obsessed with wind reading and have thought about a shooting school, but I think one challenge shooting schools have is what I call "mastery of the local conditions." You shoot at the same range over a period of years and you get pretty good, but I am not sure it transfers 100% to other areas. The mirage is thicker in Alabama than it is in Colorado, for example. Flat terrain has far more consistent wind conditions. I start every morning in CO with a shot a 910 or 1057 yards. Often the wind appears calm; the sun is just peeking out and there is no mirage. Vegetation is not moving. Yet, 9 times out of 10, there is a wind blowing left to right that requires a 1 MOA hold (I have spin zeroed for 500). I have shot enough out of my back door to realize this but new shooters who have not shot there are rather stunned.
We all know having a good wind caller is far easier than doping it and pulling the trigger so I would be interested in a school that teaches the best way to wind call going solo. Some schools supply equipment while others tell you to bring your own. I have learned the quality of the scope is huge; I love March scopes but their parallax focus sucks compared to NF; parallax focus is the way I read wind (to see mirage) if I am both doping and shooting.
Once mirage washes out vegetation is my friend but looking at the same trees blow day after day gives me a pretty good clue how to hold - at least good enough to hit 90% of the time out to 620 yards or so. Once it blows hard enough to wash out mirage it is generally gusting so frequently (and switching directions) that shooting at 1000 yards is a waste of time. Sure, you throw in a 5 MOA hold, hit, and think you are god, but I haven't seen anyone that can do that every time. I am sure what I have learned in CO is not 100% transferable to other areas in CO let alone a place like Alaska - there are no willows behind my house.
Terrain is huge; it is far more difficult to read the wind in the mountains of CO than the desert of Arizona. In CO, it is constantly shifting. But there are times CO is easier than AZ: there is a lot more debris (weed seeds) blowing in the air. When I see one blowing in my FOV, I know almost exactly what the wind is doing and shoot quickly. Rain or snow makes it much easier to read the wind - neither of these happen in desert.
I would bet a ton of money no one could hit a golf ball at 1000 yards with the first shot over two days at my CO place but if they could, it would be a great video and selling tool - and I would be eager to learn how. Hell, at 1000 yards the wind often changes during the TOF and almost always blows hard enough to move golf balls hung by a string enough to miss. I returned from CO two days ago and stopped at a place I shoot LR in the desert. I shot at 765 yards (I have a gong at 760 in CO and wanted to make sure my SIG compensated for the 7000 foot drop in elevation - it added 1 MOA as it always does). In AZ your anemometer is meaningful and the mirage is almost always there. I held 2 MOA and hit within 1/2 MOA of dead center. Shot at 1165 (different angle) and got even closer - and I had not shot in Arizona since April. My hit rate past 1000 yards is far higher in AZ than CO even though I shoot every day in CO and spend nearly all year there. My skillset is the same - the difference is the difficulty of reading the conditions as well as the fact they are constantly changing.
Certainly impressive shooting, especially considering the world record 10 shot group (heavy gun) at 1000 yards is about 50% larger than the diameter of a golf ball.
I am obsessed with wind reading and have thought about a shooting school, but I think one challenge shooting schools have is what I call "mastery of the local conditions." You shoot at the same range over a period of years and you get pretty good, but I am not sure it transfers 100% to other areas. The mirage is thicker in Alabama than it is in Colorado, for example. Flat terrain has far more consistent wind conditions. I start every morning in CO with a shot a 910 or 1057 yards. Often the wind appears calm; the sun is just peeking out and there is no mirage. Vegetation is not moving. Yet, 9 times out of 10, there is a wind blowing left to right that requires a 1 MOA hold (I have spin zeroed for 500). I have shot enough out of my back door to realize this but new shooters who have not shot there are rather stunned.
We all know having a good wind caller is far easier than doping it and pulling the trigger so I would be interested in a school that teaches the best way to wind call going solo. Some schools supply equipment while others tell you to bring your own. I have learned the quality of the scope is huge; I love March scopes but their parallax focus sucks compared to NF; parallax focus is the way I read wind (to see mirage) if I am both doping and shooting.
Once mirage washes out vegetation is my friend but looking at the same trees blow day after day gives me a pretty good clue how to hold - at least good enough to hit 90% of the time out to 620 yards or so. Once it blows hard enough to wash out mirage it is generally gusting so frequently (and switching directions) that shooting at 1000 yards is a waste of time. Sure, you throw in a 5 MOA hold, hit, and think you are god, but I haven't seen anyone that can do that every time. I am sure what I have learned in CO is not 100% transferable to other areas in CO let alone a place like Alaska - there are no willows behind my house.
Terrain is huge; it is far more difficult to read the wind in the mountains of CO than the desert of Arizona. In CO, it is constantly shifting. But there are times CO is easier than AZ: there is a lot more debris (weed seeds) blowing in the air. When I see one blowing in my FOV, I know almost exactly what the wind is doing and shoot quickly. Rain or snow makes it much easier to read the wind - neither of these happen in desert.
I would bet a ton of money no one could hit a golf ball at 1000 yards with the first shot over two days at my CO place but if they could, it would be a great video and selling tool - and I would be eager to learn how. Hell, at 1000 yards the wind often changes during the TOF and almost always blows hard enough to move golf balls hung by a string enough to miss. I returned from CO two days ago and stopped at a place I shoot LR in the desert. I shot at 765 yards (I have a gong at 760 in CO and wanted to make sure my SIG compensated for the 7000 foot drop in elevation - it added 1 MOA as it always does). In AZ your anemometer is meaningful and the mirage is almost always there. I held 2 MOA and hit within 1/2 MOA of dead center. Shot at 1165 (different angle) and got even closer - and I had not shot in Arizona since April. My hit rate past 1000 yards is far higher in AZ than CO even though I shoot every day in CO and spend nearly all year there. My skillset is the same - the difference is the difficulty of reading the conditions as well as the fact they are constantly changing.
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brant89
Well-Known Member
The only reason I used a low BC bullet at a much higher velocity was to ensure that the TOF would be shorter and the lag time would be longer so I could illustrate the relationship they have with wind drift. You can't really illustrate the mathematical relationship any other way.
LRNut
Well-Known Member
Brant:
Anyone who has shot a .224 55 grain bullet out of a Swift vs an 80 grain at far lower velocity has seen what you are illustrating. The wind drift is 2X with the lighter bullet even though it travels faster.
brant89
Well-Known Member
But most don't understand WHY it happens, and there was a lot of discussion about TOF and "the amount of time a bullet is in the wind". I'm simply trying to explain that the relationship between TOF and wind drift is not a direct one.
BrentM
Well-Known Member
Understood. It's the same reason my training rifle is a 223 running 88's vs a 55. Tof of a 55 is much lower but the 88 has significantly better performance overall. In this case tof is not a direct relationship to drift, your point. The op was directing comments to moving animals and tof not really wind but it's still an educational discussion.
Mikecr
Well-Known Member
What seemed amiss in my original post is a growing notion that higher muzzle velocity means lower wind drift.
The idea that lower TOF means wind is pushing bullets for less time. And that 'sounds' right..
LR shooters are often varmint hunters, and to reach for what 'sounds' right they'll use lighter/lower BC bullets. After all, pushing high BC bullets faster can halve barrel life, so that don't work.
But if they understand this better, and look closer, they can find better, or at least equal wind results, with higher BC bullets at reasonable MVs (and reasonable barrel life).
As brant89 is pointing out, what 'sounds' right can be wrong.
Worst IMO, is when it leads people away from better understanding.
I've seen similar crop up (in cycles) about stability. An idea that low stability can be overcome with higher MV.
An idea that stability is about faster RPMs. 'Sounds' right..
And just like this wind drift problem, a similar stability notion fails tests over & over.
The idea that lower TOF means wind is pushing bullets for less time. And that 'sounds' right..
LR shooters are often varmint hunters, and to reach for what 'sounds' right they'll use lighter/lower BC bullets. After all, pushing high BC bullets faster can halve barrel life, so that don't work.
But if they understand this better, and look closer, they can find better, or at least equal wind results, with higher BC bullets at reasonable MVs (and reasonable barrel life).
As brant89 is pointing out, what 'sounds' right can be wrong.
Worst IMO, is when it leads people away from better understanding.
I've seen similar crop up (in cycles) about stability. An idea that low stability can be overcome with higher MV.
An idea that stability is about faster RPMs. 'Sounds' right..
And just like this wind drift problem, a similar stability notion fails tests over & over.
