Installation Instructions

Bolt Carrier Group

Installation Instructions: 

IMPORTANT:  The NiB-X® AR-15 Bolt Carrier Group  is a drop-in kit replacement for the AR-15 rifle. However, the NiB-X AR-15 Bolt Carrier Group must be checked for the correct headspace by a competent gunsmith before use. WMD Guns is not responsible for chambers that are out of spec. 

Safety glasses should always be worn when replacing parts.


Remove the magazine. Unload the rifle and check the chamber. Push out the upper receiver cross pin, and remove the charging handle, bolt and carrier. Replace the charging handle and insert the NiB-X AR-15 Bolt Carrier Group into the upper receiver. Push the upper receiver cross pin into place. 


Remove the magazine. Unload the rifle and check the chamber. Push out the two receiver cross pins and remove the upper. Secure the rifle in a shooting rest or mount the rifle securely in a vise. Un-cock the hammer. (Please note that the hammer is under spring pressure, and can eject and cause personal injury or damage.) Note the position of the hammer spring in relation to the trigger and its position on the hammer. Use an appropriate pin punch to push the hammer pin from right to left while applying pressure slightly to the top of the hammer to keep the spring from ejecting it from the receiver. Next, remove the spring and install it on the NiB-X hammer. To install the new hammer, position the spring legs back over the recesses on the sides of the trigger, in the position noted while disassembling. Apply pressure to position the hammer in line with its receiver holes,  and then  push the hammer pin back into position with
its spring grooves oriented to the right of
the receiver. 

Cleaning NiB-X AR-15
Bolt Carrier Group:

WMD Guns recommends periodic wiping down of  the AR-15 Bolt Carrier Group to prevent fouling buildup and to maintain the lustre of the finish. The NiB-X AR-15 Bolt Carrier Group will operate without lubrication until a fouling buildup prevents the bolt from closing into the battery.  The number of rounds fired before cleaning varies with the firing powder. Some powders fire “dirty,” causing heavy fouling, while other powders fire “clean,” causing light fouling. Also, the use of a suppressor will leave the rifle dirtier and increase the need for cleaning. 

The NiB-X AR-15 Bolt Carrier Group should be cleaned by wiping down with a  rag. The inner diameter of the carrier should also be cleaned of carbon fouling by using an AR-15 stainless steel or bronze chamber brush. Heavy fouling may require scraping. The gas nozzle can be wiped down or scraped with a dull metal edge.

Note: the NiB-X finish may tarnish with prolonged exposure to oils and tannins in leather and from  handling. Wiping down with a rag and any standard rifle cleaning solution will help maintain the finish and prevent tarnishing. 

Little Beast


1. Open receiver, remove bolt.

2. Insert adapter assembly into chamber, close receiver. (Once installed, sights may need to be re-zeroed for the .22’s point of impact.)

Contact Form