BDC reticle question

[Mike450r]

So my kid asked me a question that spun my brain a bit so I figured I would throw it out there.

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. 

[jrebel]

I think it will tell you the rise, in inches, at 100 yards using the lower hash marks.  I would think you would have to use the 100 reticle at 200 yards to see bullet drop.  Then correspond that to the next hash mark.  If they line up then it would be your 200 yard reticle.  Very few scopes with BDC reticles are exact with yardage.  I zero mine at 200....then I shoot my 2nd 3rd and 4th hash marks (based on ballistic data of my round) to figure out where they are zeroed.  I make a 3/5 card with this data and tape it to my stock.   

[KFhunter]

The reticles are just marked as the averages of a popular loads, close but not exact.

[kingmountain]

Enter parameters for your rifle and ammo,this program will do the rest.      http://www.shooterscalculator.com/ballistic-trajectory-chart.php

[Larry S.]

OK...stand by for an info dump that will require at least  two cups of coffee.

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

[Wacenturion]

This explains things pretty well............

https://www.youtube.com/watch?v=ap8JmBvz9WM

[Alchase]

The answer to the question in paragraph 2, is no.
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.

[mazama]

I have  couple of Zeiss scopes and a Burris scopes,sight at 200yds than check at different distances,for my guns they are pretty close to on alway out to 500-700yds.

[Instinct]

i use the strelok app on my phone. put all info bout ur gun as you can including load and shows you on ur scope of what the yardages is. then i cross referance it to ballistic calculator from what bullet im using from winchester or federal...
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.

[BULLBLASTER]

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)

[WoodlandShooter]

I have two Nikon BDC scopes. They are nice, but you need to field verify your dope. It is even better if you have the BDC app. I dont really see any use for a BDC reticle past 700 yards. This is because the environmentals really start to change drop data past this range. The other issue is these BDC reticles do not have graduations to allow for wind holds.

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.

[coachcw]

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