The BMG M1919A6 has an extended front to the barrel jacket to support the bipod while the M1919A4 has a shorter barrel jacket.
Photo shows M1919A6 m/g's on the M2 tripodAttachment 37852
The BMG M1919A6 has an extended front to the barrel jacket to support the bipod while the M1919A4 has a shorter barrel jacket.
Photo shows M1919A6 m/g's on the M2 tripodAttachment 37852