JDHasty
02-22-2015, 02:23 AM
The rudiments of this discussion was included in another thread, but got me to thinking.
We have a couple Oehlers.
We ended up with a second one when the 35P came out and we wanted the printer available so we could set that one up at two hundred yards and our 33 at the muzzle and calculate ballistic coefficients very accurately and that has worked out quite well for us. We are engineers.
But you do need laboratory grade chronographs to make this scheme work out. The Oehlers can be set up with the sky screens laced to calibrate them, but our measurement between screens, from the factory, must be so accurate that no correction has ever been needed. We do this every couple years, just to make certain the 33 is working as it should. It doesn't have an independent proof channel like the 35.
You also have to hit the screen at 200 with a darn good laser, or measure it out with a surveyor's steel tape to make this a workable exercise.
With this data we can set up the 35P at 500 yards when we are chuck shooting, a lot easier now than in pre laser days, and our velocity calcs can be field validated and time of flight and bullet drop is then a known commodity out to.... wherever, I guess. In order to really accurately measure velocity loss you do need to have the very same bullet cross the screens of both chronographs. Bullet drop and friction loss are both constants with friction loss being ever so much less a constant because of head or tail wind or atmospheric conditions. Head and tail wind really is negligible.
I suppose this all goes to pot somewhere way out there, but that would only be academic and not something we varmint shooters need to concern ourselves with.
Here is how that works, the bullet drop over range is a function of time of flight. Period. No if's ands or buts about that one. If you know the time it takes for a bullet to go precisely 437 yards - you know within the accuracy of your gun, to the tenths of an inch where that bullet is going to be elevation wise. No if's ands or buts about it. It would be even more accurate if atmospheric conditions and shooting with or against the wind were not a factor. Like I said above head and tail winds are negligible and atmospheric conditions even more so.
You write a simple equation and hard program it into a scientific calculator and when you enter the range reading from your laser... voila. Dial in the elevation on your scope and if you miss high or low, look in the mirror. Or if you don't like that send your scope back and complain about the tracking.
And if you are smart you will write the equation in such a way to take into account the scale on the elevation knob that way you don't even need to figure out how many clicks. The calculator tells you where to set your elevation knob. How cool is that?
But, I hate to program, even simple scientific calculators. An entrepreneur could "hard wire" a program into $50 scientific calculator that would allow the end user to just enter how many minutes of angle the adjustment on the scope makes per click, the range and wind speed and this $50 machine would calculate both bullet drop and windage setting too. IF we are to assume that wind is steady out to the target. This means that a shooter with an accurate range finder and an anemometer and wind direction indicator (a fifty dollar investment) could put in the range and the wind speed/direction in a matter of seconds and hit the enter button and have both settings for his elevation and his windage knobs right there.
Here is how it would work: You get to a setup and decide which rifle you are going to use and which load you are going to use and select it from a menu you have entered at home. The calc already has: velocity and ballistic coefficient in it that way. Then when you spot a chuck - you hit him with your laser and put that number into the calculator. You look over at your anemometer and wind direction indicator and put the wind information in, where you are set up or if you think it is blowing, stronger, lesser, not at all or the other way "way out there" you adjust that entry up or down based on experience. And then you hit enter again.
Hint, get a ten dollar tripod from Walmart and set your anemometer and wind direction indicator out in front (just below minimum barrel height so you don't blow them away) but were you can look at the anemometer with your binocular real quick so that the wind velocity is not influenced by you, your truck and your setup.
Even without "spot on" external ballistics (the ballistic coefficient published by manufacturers, and the published velocity of the load you are using) and you are within a minute of angle of where you need to be. And the last time I checked a chuck or prairie dog subtends about a couple minutes of angle out to where we shoot them at. And if you don't have reliable data re: muzzle velocity or ballistic coefficient and are consistently hitting low or high adjust either the muzzle velocity or the ballistic coefficient up or down or up accordingly.
Now here is where this could be made even more of a useful $50 or $60 buck gadget. If you don't have laboratory grade chronograph equipment available - everyone has a laser today and can afford a hundred buck chronograph that is sufficiently reliable to set up at the muzzle (and then use the "fudge factor" that they provide to move from ten feet from the muzzle back to the true muzzle) and take ten shots and average them. Then set up your chrony, or RCBS or whatever at two hundred laser ranged yards and take ten shots and walk out and record the readings or have someone in the pit go out and write them down. Average them too and put the muzzle velocity average in to the calc and the 200 yard average velocity average in and hit a pre programmed ballistic coefficient calculator equation button and there you have it. Usable chronographs can be had for not that much money these days. A $60 - $75 calculator that lets non engineers take advantage of what he has available would be money well spent.
A competent programmer could program right into the hard programming of a simple scientific calculator features that would be a really be an asset to not only varmint shooters, but long range big range hunters as well using as a base really cheep scientific calculator platforms that already exist in today's market place.
Just an idea.
We have a couple Oehlers.
We ended up with a second one when the 35P came out and we wanted the printer available so we could set that one up at two hundred yards and our 33 at the muzzle and calculate ballistic coefficients very accurately and that has worked out quite well for us. We are engineers.
But you do need laboratory grade chronographs to make this scheme work out. The Oehlers can be set up with the sky screens laced to calibrate them, but our measurement between screens, from the factory, must be so accurate that no correction has ever been needed. We do this every couple years, just to make certain the 33 is working as it should. It doesn't have an independent proof channel like the 35.
You also have to hit the screen at 200 with a darn good laser, or measure it out with a surveyor's steel tape to make this a workable exercise.
With this data we can set up the 35P at 500 yards when we are chuck shooting, a lot easier now than in pre laser days, and our velocity calcs can be field validated and time of flight and bullet drop is then a known commodity out to.... wherever, I guess. In order to really accurately measure velocity loss you do need to have the very same bullet cross the screens of both chronographs. Bullet drop and friction loss are both constants with friction loss being ever so much less a constant because of head or tail wind or atmospheric conditions. Head and tail wind really is negligible.
I suppose this all goes to pot somewhere way out there, but that would only be academic and not something we varmint shooters need to concern ourselves with.
Here is how that works, the bullet drop over range is a function of time of flight. Period. No if's ands or buts about that one. If you know the time it takes for a bullet to go precisely 437 yards - you know within the accuracy of your gun, to the tenths of an inch where that bullet is going to be elevation wise. No if's ands or buts about it. It would be even more accurate if atmospheric conditions and shooting with or against the wind were not a factor. Like I said above head and tail winds are negligible and atmospheric conditions even more so.
You write a simple equation and hard program it into a scientific calculator and when you enter the range reading from your laser... voila. Dial in the elevation on your scope and if you miss high or low, look in the mirror. Or if you don't like that send your scope back and complain about the tracking.
And if you are smart you will write the equation in such a way to take into account the scale on the elevation knob that way you don't even need to figure out how many clicks. The calculator tells you where to set your elevation knob. How cool is that?
But, I hate to program, even simple scientific calculators. An entrepreneur could "hard wire" a program into $50 scientific calculator that would allow the end user to just enter how many minutes of angle the adjustment on the scope makes per click, the range and wind speed and this $50 machine would calculate both bullet drop and windage setting too. IF we are to assume that wind is steady out to the target. This means that a shooter with an accurate range finder and an anemometer and wind direction indicator (a fifty dollar investment) could put in the range and the wind speed/direction in a matter of seconds and hit the enter button and have both settings for his elevation and his windage knobs right there.
Here is how it would work: You get to a setup and decide which rifle you are going to use and which load you are going to use and select it from a menu you have entered at home. The calc already has: velocity and ballistic coefficient in it that way. Then when you spot a chuck - you hit him with your laser and put that number into the calculator. You look over at your anemometer and wind direction indicator and put the wind information in, where you are set up or if you think it is blowing, stronger, lesser, not at all or the other way "way out there" you adjust that entry up or down based on experience. And then you hit enter again.
Hint, get a ten dollar tripod from Walmart and set your anemometer and wind direction indicator out in front (just below minimum barrel height so you don't blow them away) but were you can look at the anemometer with your binocular real quick so that the wind velocity is not influenced by you, your truck and your setup.
Even without "spot on" external ballistics (the ballistic coefficient published by manufacturers, and the published velocity of the load you are using) and you are within a minute of angle of where you need to be. And the last time I checked a chuck or prairie dog subtends about a couple minutes of angle out to where we shoot them at. And if you don't have reliable data re: muzzle velocity or ballistic coefficient and are consistently hitting low or high adjust either the muzzle velocity or the ballistic coefficient up or down or up accordingly.
Now here is where this could be made even more of a useful $50 or $60 buck gadget. If you don't have laboratory grade chronograph equipment available - everyone has a laser today and can afford a hundred buck chronograph that is sufficiently reliable to set up at the muzzle (and then use the "fudge factor" that they provide to move from ten feet from the muzzle back to the true muzzle) and take ten shots and average them. Then set up your chrony, or RCBS or whatever at two hundred laser ranged yards and take ten shots and walk out and record the readings or have someone in the pit go out and write them down. Average them too and put the muzzle velocity average in to the calc and the 200 yard average velocity average in and hit a pre programmed ballistic coefficient calculator equation button and there you have it. Usable chronographs can be had for not that much money these days. A $60 - $75 calculator that lets non engineers take advantage of what he has available would be money well spent.
A competent programmer could program right into the hard programming of a simple scientific calculator features that would be a really be an asset to not only varmint shooters, but long range big range hunters as well using as a base really cheep scientific calculator platforms that already exist in today's market place.
Just an idea.