Complex sentence: The gun cameras, known in AAF vernacular as GSAPs, or Gun Sight Aiming Point cameras, made by Bell & Howell, were automatic and mounted on all fighters, not just those depicted in "Thunderbolt".
Split into simpler sentences: The gun cameras were known in AAF vernacular as GSAPs, or Gun Sight Aiming Point cameras. Manufactured by Bell & Howell, they were automatic and mounted on all fighters, not just those depicted in "Thunderbolt".