Nikon BDC, Burris Plex. What magnification for its function?

[Orion8472]

The Bullet Drop Compensator, for the Nikon, and the Plex for the Burris, are supposed to make longer distant shots simpler by using the lines/circles under the crosshairs as you target out further. However, these scopes are not fixed power, but variable. How can you realistically use a BDC/Plex if, when you up the power, the sight picture changes from power to power? For example, if you have your scope set to 5 power, looking at the sight picture will put those circles/lines on a different point than if you up the power to 14.

Anyone have a comment how this is over come, . . . or is there a specific magnification that you have to have it on before the BDC/Plex works?

Thanks!

 

[smokey262]

Usually you need to put the scope on max power for these reticles

 

[Orion8472]

I asked this on a dedicated optics forum and that seems to be the opinion of one of them on there, too.

 

[Jaybird78]

Nikon BDC

Instructions on web.

Set magnification at you preference for X yards. Fire three shot group. Go down range and use a sharpie, etc. to mark center of the group. Go back to the rifle/scope and adjust magnification ring up or down until top/bottom/center of which ever circle centers over your sharpie center mark. Record the magnification setting and circle for your center. Use these SAVED SETTINGS for particular load to give follow up shots at X yards.

Poor man's mil-dot so to speak.

I am in the process of using the Nikon BDC. I just got my hand load down and now I have to start shooting at different ranges to record settings for my pet load. I shoot mostly at 1/2 gallon jugs and soda cans. FWIW

Good Luck

 

[ArmedBear]

For the Burris Ballistic Plex, the scope has to be set to the maximum power if you want the tick marks to be easy to use. I wasn't clear on that, either, so I asked Burris. Burris' system has marks for 200, 300, 400, 500 yards, or 300, 400, 500 and 600 for flat-shooting rounds. The scope is initially zeroed at 100 or 200, depending.

I have a 3-9x scope with the Ballistic Plex reticle. Sure enough, if I sight it in at 100 yards, I can use the tick marks and hit dead on at longer ranges. I've had fun popping small balloons I've set up on BLM land with the thing, as practice for hunting, and the reticle does work quite well.

I think the logic behind setting them up for the highest power is that holdover really doesn't become relavent until you shoot past 150 yards (250 for flat-shooting rounds that are zeroed in at 200, like the .270 or the faster magnums). Once you're shooting that far, you probably crank the scope anyway. Certainly, at 300+, I do.

 

[Orion8472]

Thanks for the posts.

I decided to get the Coyote because, on the website, it seems to be set up for .223. Having said that, one can never really know where any specific load will hit. I have Privi Partizan 62 grain fmj rounds that will not hit the same place as 55 grain Winchester.

If I buy one of these scopes, I guess I will be only using my Black Hills 52gr. rounds to find what magnification for the circles to use.

 

[skoro]

I have both the Nikon BDC and Burris plex on different rifles. The BDC is 3-9x and the Plex is 2-7x. As others have already stated, it works best for me at max magnification.

 

[sscoyote]

They are all 2nd or rear focal plane reticles. The significance of this is that as the power is changed the measurement (subtension) between stadia change. The best way to understand this is to look at some object at a distance. While keeping the x-hair on some point u should see that as u change the power the stadia change their location on the object. It's actually inversely proportional (power vs. subtension). The system (subtension) is measured in minute of angle (MOA) or inch per hundred yds (IPHY). Ballistics programs calculate bullet drop and drift in MOA and IPHY, so it can be matched to a reticle's subtension. If u go to the Burris website they explain all the systems that can be established for 2nd FP reticles. They have an excellent writeup on that site.

 

[Orion8472]

Is this the same for the Nikon, or just the Burris?

 

[sscoyote]

Both. If u have a scope where the reticle is located in the 1st focal plane u will notice it right away as this is also called a "magnifying" reticle and the reticle gets smaller and larger as the power is changed. In this case the subtension between any 2 reticle points stays the same downrange no matter what power u r on.