I am building a 18 inch SPR in 5.56. I am interested in the NF NXS 2.5-10 x 32. The Velocity reticle calculator stated I should get the Velocity 600. I personally like how the Velocity 1000 looks over the 600. I also like the mil dot reticles as well. I normally use Aimpoints, and ACOGS. This will be my 1st SPR build, and my 1st NF optic. Ammo I will be using is Federal Gold Metal Match 77 grain, and other 75 to 77 grain ammo. Please any feed back on this would be helpful in my optic choice. Also feed back on use of the Velocity 600 pros and cons would be helpful. thanks