Pros/Cons of Nikon's BDC Reticle
01-26-2015 | 08:40 AM
#21
Giant Nontypical
Joined: Dec 2007
Posts: 5,130
Likes: 0
From:
While I'm not usually one to take interest in a 7yr old thread, I'll bite...
I agree with Sheridan, that the large subtension of the circles makes them a rather bad choice, especially at longer ranges where precision POA placement becomes more and more critical.
My major problem with BDC reticles, even with the SpotOn programming, is that they're only valid under one singular set of conditions. Changing ONE variable for environmental conditions will throw the SpotOn estimates for range/circle reference out the window.
For example, WITHIN A MATTER OF WEEKS, I hunted coyotes in these conditions last season:
I did some test shooting to rezero my rifles and test trajectory when I changed conditions. Luckily for me, I was using Varget and didn't get a lot of velocity spread, but my 400yrd drop changed pretty significantly - enough to have caused the difference in a well placed shot and a dead coyote, and a bad shot, or even a miss!!
Central KS 0 degrees, 1200ft 400yrd drop = 36.5" (This is my normal zero)
Eagle colorado, 0deg, 6700 ft 400yrd drop = 30.5"
Maricopa AZ 65degrees, 1200ft 400yrd drop = 32.25" (Same conditions I might hunt in at home during spring/fall, but drier air)
So if I simply relied upon my BDC reticle and SpotOn's estimation for my cold day zero at home, I might have missed by 4-6". Equally, if I zero in the winter then hunt in the spring here at home, I'll see the same type of variability for drop at range.
Now add to that temperature sensitivity for powders. I run IMR 4064 in my .30-06, which has kicked me in the teeth before when we had a heat wave during rifle season, as a -10 degree day runs the same load about 130fps slower than a 65degree day, hitting about 7" higher at 450yrds.
DOPE books and ACCURATE range cards are worth a lot. BDC reticles aren't worth jack.
I agree with Sheridan, that the large subtension of the circles makes them a rather bad choice, especially at longer ranges where precision POA placement becomes more and more critical.
My major problem with BDC reticles, even with the SpotOn programming, is that they're only valid under one singular set of conditions. Changing ONE variable for environmental conditions will throw the SpotOn estimates for range/circle reference out the window.
For example, WITHIN A MATTER OF WEEKS, I hunted coyotes in these conditions last season:
I did some test shooting to rezero my rifles and test trajectory when I changed conditions. Luckily for me, I was using Varget and didn't get a lot of velocity spread, but my 400yrd drop changed pretty significantly - enough to have caused the difference in a well placed shot and a dead coyote, and a bad shot, or even a miss!!
Central KS 0 degrees, 1200ft 400yrd drop = 36.5" (This is my normal zero)
Eagle colorado, 0deg, 6700 ft 400yrd drop = 30.5"
Maricopa AZ 65degrees, 1200ft 400yrd drop = 32.25" (Same conditions I might hunt in at home during spring/fall, but drier air)
So if I simply relied upon my BDC reticle and SpotOn's estimation for my cold day zero at home, I might have missed by 4-6". Equally, if I zero in the winter then hunt in the spring here at home, I'll see the same type of variability for drop at range.
Now add to that temperature sensitivity for powders. I run IMR 4064 in my .30-06, which has kicked me in the teeth before when we had a heat wave during rifle season, as a -10 degree day runs the same load about 130fps slower than a 65degree day, hitting about 7" higher at 450yrds.
DOPE books and ACCURATE range cards are worth a lot. BDC reticles aren't worth jack.
With a BDC reticle you always need to verify your POI at 200, 300, 400 and so on.
IMHO BDC reticle are worth more than "Jack" if you verify your POI with the environment and load.
100% Agreed that BDC are not accurate enough beyond 500 yards.
Doping the wind is a whole other story !!!
02-08-2015 | 09:52 AM
#22
Nontypical Buck
Joined: Oct 2009
Posts: 3,938
Likes: 3
From: Kansas
I suppose that I should clarify my statements about why I find the BDC reticles worthless...
The BDC reticles essentially make you rely upon software to produce a shooting solution that may or may not be accurate, and IS in a form that is rather hard to use, rather than relying upon DOPE (data on previous engagement).
The graduations (measurement unit indicators) on the BDC reticles are not consistent, and the resulting ranges are relatively random. It forces the shooter to remember the scope's subtended ranges, rather than simply remembering their load's trajectory, and pray that they can estimate drop over range between the two points.
For example - my wife has a Nikon 4.5-14x40mm with Nikoplex, but the same scope is available in a BDC, so I'll run that through their SpotOn software.
If I strapped that on top of my .30-06 (using this as an example because I know that load very well), here's what I'd come up with:
At home with my "winter zero" of 20degrees and 1225ft elevation, Nikon's SpotOn software shows a 100yrd zero and set on 14x would give:
214
316
402
522
625yrds (top of the bottom reticle post)
But under the conditions I shot in Eagle a couple months ago, the same load would show:
221
332
429
569
692yrds
Change my temperature, at home to a warm spring/mild summer afternoon, where I know my velocity gains ~130fps over a certain powder:
227
341
439
574
690yrds
Lots of random ranges... But I guess it's ok that I can re-run the numbers easily enough. Kinda sucks to have to put my target at 574yrds or 439yrds to confirm that the circle is "Spot On" though...
So I range a coyote at 481yrds on a warm day here at home. I don't know anything about my trajectory, I only know what ranges the circles would be on target. Now I have to eyeball the hold over between a 439yrd and 574yrd spot. Half way between the two circles will not represent a hit at half way between the ranges, so even if I take the average of the two in my head and figure out that half way between them is 506.5yrds, I don't actually know where my bullet is hitting between those points...
But wait - what if I'm at 7x instead of 14x? The second focal plane reticle will change in subtension, but how does it change? The gap between each subtension SHOULD double, but what's the reference frame in terms of range? According to the software, at 7x on that warm spring day:
321
509
664
864
1025yrds
Edited by JW Reason Language...... do I do with that? I've shot this rifle and this load for almost 20yrs in various environmental conditions across the US, and I have made several 400-600yrd shots with this rifle on game... After reading these output reports from the BDC software, I feel like I have no idea (edited by JW reason Language) I'd be aiming at...
Comparatively - let's say I was shooting a mil-dot reticle...
I've shot my rifle at known ranges under known conditions, and I wrote down the different trajectories.
So now I'm looking at that coyote out at 481yrds. I know that it's a hot day compared to my "winter zero," so my rounds are cooking off ~130fps faster than normal, and my range card already has notes to help me account for the temperature change. I know that at 450, my round at that temperature and elevation would be 2.1mil low, and at 500, she'd be 2.5mil low. 481yrds is a bit over half way, so I'll assume the drop will be about half of that gap. So I plan a hold of 2.3mil, and send the bullet onto target.
Sure seems like I'll be a lot faster and a lot more accurate figuring hold with a mil-dot reticle and DOPE book than I will with a bunch of lists of random @ss ranges and an app on my phone. The BDC's work great if you're under the exact conditions that you ran the software for, and the target is at the exact ranges that are represented in the circles, but if not, you're screwed.
(Not to mention if I don't get service where I happen to be shooting on that particular day.)
The BDC reticles essentially make you rely upon software to produce a shooting solution that may or may not be accurate, and IS in a form that is rather hard to use, rather than relying upon DOPE (data on previous engagement).
The graduations (measurement unit indicators) on the BDC reticles are not consistent, and the resulting ranges are relatively random. It forces the shooter to remember the scope's subtended ranges, rather than simply remembering their load's trajectory, and pray that they can estimate drop over range between the two points.
For example - my wife has a Nikon 4.5-14x40mm with Nikoplex, but the same scope is available in a BDC, so I'll run that through their SpotOn software.
If I strapped that on top of my .30-06 (using this as an example because I know that load very well), here's what I'd come up with:
At home with my "winter zero" of 20degrees and 1225ft elevation, Nikon's SpotOn software shows a 100yrd zero and set on 14x would give:
214
316
402
522
625yrds (top of the bottom reticle post)
But under the conditions I shot in Eagle a couple months ago, the same load would show:
221
332
429
569
692yrds
Change my temperature, at home to a warm spring/mild summer afternoon, where I know my velocity gains ~130fps over a certain powder:
227
341
439
574
690yrds
Lots of random ranges... But I guess it's ok that I can re-run the numbers easily enough. Kinda sucks to have to put my target at 574yrds or 439yrds to confirm that the circle is "Spot On" though...
So I range a coyote at 481yrds on a warm day here at home. I don't know anything about my trajectory, I only know what ranges the circles would be on target. Now I have to eyeball the hold over between a 439yrd and 574yrd spot. Half way between the two circles will not represent a hit at half way between the ranges, so even if I take the average of the two in my head and figure out that half way between them is 506.5yrds, I don't actually know where my bullet is hitting between those points...
But wait - what if I'm at 7x instead of 14x? The second focal plane reticle will change in subtension, but how does it change? The gap between each subtension SHOULD double, but what's the reference frame in terms of range? According to the software, at 7x on that warm spring day:
321
509
664
864
1025yrds
Edited by JW Reason Language...... do I do with that? I've shot this rifle and this load for almost 20yrs in various environmental conditions across the US, and I have made several 400-600yrd shots with this rifle on game... After reading these output reports from the BDC software, I feel like I have no idea (edited by JW reason Language) I'd be aiming at...
Comparatively - let's say I was shooting a mil-dot reticle...
I've shot my rifle at known ranges under known conditions, and I wrote down the different trajectories.
So now I'm looking at that coyote out at 481yrds. I know that it's a hot day compared to my "winter zero," so my rounds are cooking off ~130fps faster than normal, and my range card already has notes to help me account for the temperature change. I know that at 450, my round at that temperature and elevation would be 2.1mil low, and at 500, she'd be 2.5mil low. 481yrds is a bit over half way, so I'll assume the drop will be about half of that gap. So I plan a hold of 2.3mil, and send the bullet onto target.
Sure seems like I'll be a lot faster and a lot more accurate figuring hold with a mil-dot reticle and DOPE book than I will with a bunch of lists of random @ss ranges and an app on my phone. The BDC's work great if you're under the exact conditions that you ran the software for, and the target is at the exact ranges that are represented in the circles, but if not, you're screwed.
(Not to mention if I don't get service where I happen to be shooting on that particular day.)
Last edited by JW; 02-09-2015 at 05:03 PM. Reason: Ruke #1 Language
