On AR-15 rifles, like the m16, what is that small metal cylinder, on the right-hand side?
Forward assist known also as a bolt assist. Helps put the bolt into battery if the bolt hangs up for some reason. This was put on M16’s after the XM16E1 which became the M16A1. In addition, the Army insisted on the inclusion of a forward assist to help push the bolt into battery in the event that a cartridge failed to seat in the chamber through fouling or corrosion. Colt had argued the rifle was a self-cleaning design, requiring little or no maintenance. Colt, Eugene Stoner, and the U.S. Air Force believed that a forward assist needlessly complicated the rifle, adding about $4.50 to its procurement cost with no real benefit. As a result, the design was split into two variants: the Air Force’s M16 without the forward assist, and for the other service branches, the XM16E1 with the forward assist.
