This AR-15 M4 upper receiver parts kit has the small parts you need to finish a mil-spec stripped upper receiver. It includes a complete forward assist assembly and a standard ejection port cover (dust cover) assembly, with the pins, springs and clips each one needs.

Use it when you buy a stripped upper for a new build, or to replace a lost spring, a bent dust cover door or a worn forward assist on an existing upper.

Kit includes:

• Forward assist
• Forward assist spring
• Forward assist retaining pin
• Ejection port cover door
• Ejection port cover spring
• Ejection port cover C-clips

This kit fits mil-spec AR-15 stripped uppers that have a forward assist boss and an ejection port cover hinge. Slick-side uppers without a forward assist only use the dust cover parts. During install, support the upper in a vise block, and take care that the forward assist roll pin does not mar the receiver. After assembly, check that the dust cover snaps open when you press the bolt release, and that the forward assist returns freely.