Post by: Mike450r on December 19, 2014, 10:45:34 PM
If you have the 100 yard crosshair zeroed at 100 yards and then shoot at the hundred yard target using the 200, 300, 400 yard drop crosshairs would the number of inches it shoots high correspond to the drop at those distances.
My initial answer was no as different loads woulld have different drop but the inches high at 100 should be relatively consistent regardless of load and bullet. Then I started second guessing myself and head started hurting thinking about it.
So before I go find out by throwing lead I figured I could see what somebody else thinks or knows.
Post by: jrebel on December 19, 2014, 10:57:53 PM
Post by: KFhunter on December 19, 2014, 11:12:07 PM
Post by: kingmountain on December 20, 2014, 07:48:18 AM
Post by: Larry S. on December 20, 2014, 09:57:28 AM
Assuming (1) That you are using the one type of ammunition that you've chosen to hunt with, that you've proven to yourself that that type of ammunition (manufacturer, bullet style, bullet weight and initial velocity, etc.) will consistently give you good groups; (2) That your rifle is capable of consistent groups (cleaned regularly, all screws tightened and torqued to proper settings, all scope mounts and rings tightened and torqued to proper settings); (3) That you are shooting from a stable and firm rest; and (4) That you have your scope set to the magnification specified by the manufacturer in order to use the BDC, (and, unlike me in too many instances, remember to set that power when you're about to shoot), then here's something that may help you:
(A) Use a ballistic calculator to plot the trajectory of your bullet out to at least 500 yards. The calculator mentioned by an earlier responder is a good one and there are several others on the internet that you can also run for comparison. Always use one that lets you enter parameters for weather, altitude, scope height, atmospheric pressure, etc.
(B) Run the program five times. Once for a 100 yard zero. Once for a 200 yard zero. Once for a 300 yard zero, etc.
(3) Note that the bullet trajectory graphs of the five different examples will show that the bullet height at 100 yards gets higher for each example run. For example, with a 100 yard zero, the bullet will be dead on at that range. With a 200 yard zero, the bullet trajectory (path) at 100 yards will be somewhere around 2" high. For the 300 yard zero, the bullet path at 100 yards will be a bit higher, etc., all the way out to 500 yards (or farther, if you wish).
(4) Using these increasing bullet trajectory heights (at 100 yards) take a target and place an aiming dot at the center of the target. That will be your 100 yard zero. Move a bit to either side and place aiming dots along a line (at the same horizontal height) for 200, 300, 400, and 500 yards. Then, using the 100 yard bullet trajectory heights you noted out to 500 yards, place a target (impact) dot above each aiming dot at the appropriate height for that range.
In other words, you should now have a target with 5 different aiming and (above them) impact points. One level will have your aiming dots at the same horizontal height for 100, 200, 300, 400, and 500 yards, and the second level will have impact dots at successively higher points above those aiming dots. Using your scope's BDC, shoot at each aiming dot with the appropriate hash mark/crosshair/flyspeck/dirt granule (I need excuses for when I miss) and you should be OK.
(5) Whew!
(6) It works. I've even checked this with tech reps at Leupold (since I don't have a 500 yard range where I can shoot) and they agree that it's a sound plan.
(7) Go shooting and have some fun. You'll love it when your bullet hits the impact dots at each successive height proving that physics is not just a good idea. It's the law!
Long-windedly,
Larry Simoneaux
Post by: Wacenturion on December 21, 2014, 04:05:23 PM
https://www.youtube.com/watch?v=ap8JmBvz9WM (https://www.youtube.com/watch?v=ap8JmBvz9WM)
Post by: Alchase on December 22, 2014, 08:48:08 PM
If you shoot a 100 yard target with you 200 yard reticle it will not correspond to the drop because the drop increases with loss of velocity from air resistance and lose height because of gravity. The parabolic shape of a trajectory is the result.
Post by: mazama on December 24, 2014, 05:59:29 AM
Post by: Instinct on December 27, 2014, 11:27:00 PM
my buddy who introduced me to the app said it was accurate from the reviews and what nots.
i havnt tried it yet due to sending my scope in for repair but should be back on the 30th.
Post by: BULLBLASTER on December 28, 2014, 08:31:29 AM
Post by: WoodlandShooter on December 29, 2014, 09:08:01 AM
on my stuff that I use to go to 1000 yards and beyond, I dont use a "BDC" reticle. Personally I like MLR type reticles in a Front focal plane.
I have four apps for dope on my brick.
Applies Ballistics, Ballistics AE, a modified Pesja Excel Spreadsheet, and the Nikon BDC APP.
Post by: coachcw on January 13, 2015, 06:17:30 AM
keep in mind that with most of the BDC reticals the drops will change as the scopes power is adjusted (the second line may be 300 yards on 12 power but wontbe the same on 6 power)most critical point . you can look at ballistic data to figure out what power you need to be on for 200-600