Compact Assault Rifle - Suppressed - 5.56x45mm NATO - USA - 825 RPM - The M4A1 (Colt Model 927) is the most recent variant of the CAR15 family.  The barrel length was specially selected to provide compactness without sacrificing reliability.  The barrel is also contoured to provide for the attachment of a M203 grenade launcher.  It also has improved handguards to prevent the uncomfortable heating properties of earlier CAR15s during rapid fire.  Many companies are now offering quick attach suppressors for the M4A1 which only require the use of a modified flash hider.  Designs like the Knight Armament Company suppressor can provide 28db of sound reduction even with supersonic service ammunition like the M855.  D.E. Watters