The CR has four holes at the muzzle end and is called a "brake" by Browning. A picture of one is attached in post # 25 in the thread http://benchrest.com/showthread.php?...-muzzle-brakes.
The rifle shoots tight with the brake tuned, easily sub-MOA even with Remington Core-Lock 150 grain ammo. Same ammo in an unmodified 1903A1 Springfield shoots far looser. Yes, the BOSS and the BOSS CR work to reduce group sizes.