A Marine and his rifle makes perhaps one of the most individually lethal combinations on the planet. Marines and their rifles, even deadlier, and battalions, supported by individual and combined arms one of the most feared and revered fighting organizations on the planet.
However, all that efficiency is not just from Espirit de Corps. Much of this is owed to the fanatical attention to logistics and training that Marines receive on an ongoing basis. To ensure that training is the same fleet wide, the Marines (like many bureaucracies) create comprehensive manuals that cover the weapon in extreme detail. These manuals are the backbone of how the organization services its weapons systems at the field, armorer, and depot levels.
In this case, we have ourselves TM 05538/10012-IN, a completely boring set of numbers for the US Marine Corps Technical Manual, Organizational and Intermediate Maintenance Manual with Repair Parts List for the M16 and M4 series of weapons circa December 2008.
The manual is a wealth of information on the basic nomenclature, maintenance, and troubleshooting of the M16/M4 series of weapons. The manual covers in detail many of the common and a few not so common issues found on the weapons and their resolution at the armorer level.
For weapons nerds, this is a treasure trove of information. A copy of the manual can be found here at Info.PublicIntelligence.net