quote:

Originally posted by Ackley Improved User:
Don't think I could stabilize that 80 gr AMAX - my twist rate is 1 in 12".

quote:

Originally posted by Ackley Improved User:
Guys,

For fun I'll use the advanced wind kit supplied by Ballistics-Advanced and calculate windage in MOA, after you define wind conditions for your shot and how much windage you provided to make you shot.

I would want you to give me...

1. Altitude (or absolute barometric pressure) and temperature - clearly, air density effects the windage calculation.
2. Distance in yards to the target with the uphill/downhill angle, if relevant.
3. Detailed description of the wind - relative to the LOF - using anemometer for wind speed at FFP (ie., if you have one) and wind speed "feel" downrange using traditional wind estimate observations, as well as mirage angle by spotting scope.
4. Sight height, Zero point (with or without any vertical or horizontal offset), bullet data (weight, BC, length) and muzzle velocity corrected for temperture (assume ammo temp = ambient temp) for ToF, spin drift, cross-wind jump, Coriolis effect (for very long shots will need azimuth and LoF), vertical solution, etc. I'll assume right-hand twist unless told otherwise.

I'll tell you how long it takes me to calculate the windage, and then we'll compare the computed solution to your solution, based on your experience alone and actual observed hit point.



Let do it.

Regards, AIU

quote:

Originally posted by Ackley Improved User:
Try StrelokPRO (10$) - I think you'll like it even better, but its wind is traditional (i.e., constant) and not as versatile as wind kit of Ballistics/Advanced.

Time permiting, one could solve for wind with Ballistics and otherwise use StrelokPRO for hunting.

quote:

Originally posted by AnotherAZWriter:

quote:

Originally posted by Ackley Improved User:
Try StrelokPRO (10$) - I think you'll like it even better, but its wind is traditional (i.e., constant) and not as versatile as wind kit of Ballistics/Advanced.

Time permiting, one could solve for wind with Ballistics and otherwise use StrelokPRO for hunting.

I tried the Bal/Adv yesterday. Will write more when I have time, but the feature to put in different wind patterns is detrimental to the product; I shot a .338 Lapua and a Swift (80 gr AMAX) yesterday. After shooting the Lapua, I switched to the Swift and it had LESS wind drift than the Lapua. I spent several minutes trying to figure out what was going on. Eventually found the wind was not constant across the range (a thin slice of wind instead of a constant wind across the range). Once I fixed that, it had a solution that made sense.

I do like the way you wipe the wind speed direction, but you have to remember to point it in the direction the wind is going, not from where it is coming.

But I will say I am glad I bought it and thanks AIU for digging in your heels. But it won't solve the problem of wind by itself. I found the biggest value was sitting there and evaluating different wind conditions - they varied by as much 4.5 MOA depending on speed and direction. The time it takes to use causes you to think a little bit more about the exact wind condition you want to shoot in, instead of looking at the scope (mirage), the wind activity, the anemometer, and making a decision.

Incidentally, if I just entered the anemometer speed and angle I would have missed by a country mile. More when I have time.

quote:

Originally posted by Dogleg:
I shoot year round on my own range. Summer temperatures tend to be 15-30 C and we will regularly shoot to -20C and occasionally down a bit colder than that. There's a fairly consistent 1 MOA correction needed at 650-800 yards between the two extremes with loads that are less temperature sensitive. Part of that will be the velocity drop, and part from the heavy air. I'll alternately add the minute for the winter conditions, slip the scale 1 minute or in the case of a couple of favorite rifles use summer and winter loads. An extra grain of powder seems to make a lot of the "problem" go away.

We were out plinking yesterday, mostly at 650 and 800 yards. The head of a steel IPSC target is a fun target once a few sighters have been thrown out there.

Here's the situation. I've got 4 flags spaced out from the shooting position to 800. Yesterday the wind would be sometimes blowing in 3 different directions just to get to 650.As often as not the mirage would be going the opposite direction as the 650 flag. Ranges up to 500 are partially protected on left to right winds by a tree line, but take the brunt of it of a right to left wind. Shots at 650 and out are above the trees the whole way. An elevated flag at 200 well above the trees would often show that the wind at that point was perhaps 3 times the force as at the relatively sheltered shooting position and usually in a different direction. A headwind from the 800 yard target has to jump a 30+ degree slope down to the lake at approximately 200 yards and if my calculations are correct gives a lift/deflection equal to a half force wind. At just 650 the mirage will lift the POI up to 1 1/2 MOA on the boil though usually closer to 1 MOA. When the mirage flat lines with higher surface wind speeds, or disappears in the morning or evening the elevation correction isn't needed. The 800 yard targets have the bullets flying over the tree tops, across the corner of the lake which has the 30 degree wind modifying slope mentioned before, above about 10 percent of the eagles and down into the targets that are in a opening in the bush that masks the mirage.


What would be a good ballistic program for me? I'd like one that gives simple answers even when there isn't one. Mine isn't working, and my Kestrel has been working as a paperweight as of late.