Joe, I don't disagree with your comments about chasing shots, but watching and participating in long range shooting it is apparent that many people do not chase their shots nearly enough.  Many people seem scared to do it and it costs them.  I know I am generally too conservative about changing my sights more often than not.

Brent

Quote:

Brent,
  I do not mean to discount what you say, and as a matter of fact, now that I think about it, I believe this anamoly struck me down at a long range match last year. I was shooting at the 1000 yard target, and spotting for myself. The mirage indicated a left to right wind, and I adjusted windage accordingly during my sighter shots. During the relay for score, my shots started going out left. The darn thing is, the mirage was still running left to right, with virtually unchanged conditions. I was a little too flummoxed to really grasp what was going on, and ended up chasing my shots back on target. It really defied anything that I had learned about shooting and spotting. Somehow I managed to place second in that match. A real head scratcher that one. It's been bugging me ever since. Thanks for the insight!

Bill

I learn something new all the time on this forum! Sometimes it beats all the magazine subscriptions I have! 

Bill

JD, just to add a little mirage to the discussion, at Etna Green this May, there was a bit of discussion and experimentation concerning when in the bullet's path the greatest wind effect is observed.  I was amazed to find that when there was a lot of wind out near the target, I had to pay more attention to the 175 yd flag than to the 50 or 75 yd flags.    I still didn't win anything, but I was able to close up my groups significantly by changing my emphasis on which wind flags to watch most carefully.  Don't ask me what any of this means, but it was an empirical observation.   

Froggie

Jims right any wind will affect the bullets strike. you have to watch all of it.   

You always hear the wind has more effect at muzzle. Strickly speaking this is not true, winds effect on the bullet is almost the same muzzle to target.   The significant effect on strike is angle of departure.

At muzzle any defection  will have more effect on target than deflection down range , it's due to the angle, longer distance more the bullets strike is off.

Wind itself blows the bullet off nearly the same muzzle or target. Except the bullets sensitivity to wind at lower velocity. This is mimimal.

Boats

In ASSRA matches with unlimited sighters you are better off reading condition with strikes on the sighter target. Trying to figure it out from flags and mirage has it's pitfalls.  Shoot the most adverse condition read the strike, then shoot the condition you are probably going to use read that strike and use flags to alert you to changes. Any change go back to the slighter.

Reading flags ior mirage is mostly for matches were no or limited sighters are the rule.  Even on those matches oftentimes a team will use a sacrificial shooter to hold center with mechanical zero on the rife to read the wind by observing strike

Boats

Jim, you're right about the time increase in the last 100 yds, but consider this: in diametrically-opposed crosswinds the bullet's angle of departure has been immediately affected by the wind at the muzzle and the bullet is thus already moving sideways at an angle before it ever gets to the 100 yd line. If it then encounters an opposite crosswind, the wind will not only have to counteract the angle of the bullet's path but it will also have to make up the sideways distance already travelled. IOW if you have a 9:00 10 mph crosswind from the left for the first 100 yds and then a 3:00 10 mph crosswind from the right (exactly opposite) for the last 100 yds, then I'll bet your bullet will land somewhere to the right of the bull because the early wind changes the angle too much to overcome.

The reason for this can be found in the geometry of the shot. It's true that the later angular change caused by the second-100-yds wind is greater than the initial angular change caused by the wind at the muzzle because the bullet is traveling slower and therefore the wind has more time to act during the second 100 yds, but it's also true that the second angular change is measured not from the line of the barrel but rather from the line of the bullet's existing path which now has a sideways vector. A moment's thought will show that the second angular change will do slightly more than correct the bullet's path back to being parallel with the bore line, the difference being due to the slower velocity during the last 100 yds. However the bullet has already traveled sideways a considerable distance and it simply cannot make it up in the time remaining with the relatively small angular correction achieved.

Let me put it another way: let's say you have one shot fired in a crosswind at the muzzle that dies out completely at the 100-yd line, and you have another shot fired in an identical-speed crosswind that does not begin until the 100-yd line and continues to the 200-yd target. Which one will be blown further off the 200-yd bull? Let's just say that the first shot would be blown 2 inches sideways in the first 100 yds; then it's logical to say that the second shot will be blown more than 2 inches sideways in the second 100 yds since it's traveling slower, right? But probably not a whole lot more than 2 inches since it's really not traveling that much slower, right? So let's just say 3 inches even though it wouldn't be that much. So our second bullet hits 3 inches out.

But we can't forget that second 100 yds that must still be traveled by the first bullet, the one that was blown sideways 2 inches in its first 100 yds. True, it was displaced an inch less than the second bullet, but that was only up to 100 yds! It will continue to travel the second 100 yds as a direct extension of its path in the first 100 yds and end up ~ 4 inches off at 200, noticeably more than the other bullet. I believe this is one of Newton's laws, the one that says a body in motion will continue its direction and speed unless affected by some other force.

This is a rather simplistic explanation and I hope I've been clear enough. I still have nightmares about my struggles in Physics 101 40 years ago, not to mention Statics and Dynamics!
Regards, Joe