www.gggaz.com/products/ar-10fire.php

The caliber .308 Winchester AR-10 rifle is becoming increasingly popular in law enforcement circles for use in their selected marksman programs and among civilian shooters interested in working at long ranges. Our FIRE (Fully Integrated Rifle Enhancement) System dedicated to the AR-10 provides you with the flexibility to design a weapon system to meet your particular MENS (Mission Essential Need Statement). The AR-10 FIRE System includes two different interface rails, a MAD BUIS Flip Up Rear Sight and an easy-to-install Tactical Modular Flip Up Front Sight System. For long-range shooters requiring additional elevation, we offer a custom GS-1 and Scout rail with 15 MOA of elevation built in. The AR-10 FIRE System can be purchased as a complete set or as individual components.

What does this mean when they say that the rail has 15 MOA built in?

I understand the concept of MOA as it pertains to "my rifle fires 1 MOA", but I'm not sure how the rail adds 15 MOA elevation.

If using an Aimpoint mounted on the rail moves where the bullet will hit up 15" at 100 yards, wouldn't this increased elevation MOA be different depending on the placement forward and back on the rail?

What they mean is that the mount is slightly lower in the front than in the rear. This tilts the scope a little, so that you can shoot long range, without bottoming out the scopes' elevation adjustment. Nope. A "straight" rail would be parallel to the bore, while a "15 MoA" rail is on an intersecting plane. The whole rail will be 15 MoA off parallel, so it wouldn't matter where on the rail the optic is mounted. Rails with elevation built-in are designed for shooting at REALLY long range with a high-magnification scope, so you'd be much better off using a regular straight rail with an Aimpoint, IMHO.

Absolutely brilliant.

Thank you, I learn something new every day.