Is'nt this scope designed to be used with a 28" Barrel, a 250gr Bullet and 150 gr's of Pyrodex. From what I read this is the load you have to use to have the BDC work properly. Anyother load bullet combination used you will then have to (Guess) as to where to hold on the BDC.
That's why I went with the Leupold Ultimate Slam ML Scope. With this one it has (3) different settings, one for a Shotgun, one for 2-pellets and one for 3-pellets, you get more options with the Leupold and there about the same in cost.
Excuse me if Im wrong about the Nikon, but I think that's what it says about it. Also I was'nt to thrilled to find out that when using the Leupold's BDC you have to have your scope set at 9power all the time when using the BDC.
Let me know how you make out with the Nikon, best of luck to you!
BP