Charles Daly D-M4LE Carbine Guide and Review

[Stickman]

Inside the upper receiver we have what many will argue is the most critical part of the weapon, which is the Bolt Carrier Group (BCG). To start, the barrels are randomly proof fired, and then barrels and bolts are batch Magnetic Particle Inspected (MPI). While this isn't something that shooters will ever notice, its a nice step to ensure quality is staying on track in the production line.

The top of the BCG houses one of the weak links in the AR15, and of course that is the Carrier Key. Staking the Carrier Key provides that the screws will not rotate or vibrate loose. When this loosens, gas bleeds and begins to cause short stroking in the system. There have been a lot of unhappy shooters with issues traced back to a loose Carrier Key. Proper staking causes enough metal to displace, and contact the screw head which locks them in place. While heavily staked, CD has made sure they do not encroach above .025 which is the max allowed for Mil Spec.

For those readers who feel that the proper staking is something which can not be over emphasized, here are two pictures to illustrate the staking from different angles.