Dust cover part replacement

[drkphibr]

Anyone know what the part in the pic is called (dust cover latch)? On my Colt 22 M4, it's missing the nipple. I called them for a replacement and they said it's by design. Funny, since my Colt M16 has a working dust cover and the attached pic below is from their web site showing the disassembly and maintenance process on the exact M4 22LR I have. Looks like a functioning dust cover to me. I guess you roll the dice with customer support sometimes.

I'm sure the part is available someplace or do I actually need to replace my entire dust cover? Any help appreciated. Thanks.

[mindwip]

I know a lot of tact .22s are ar clones, can you just buy the ar part?

[Tank 57]

I think the part is called a "detent".

[kris&bela]

part #9 (576.30.02.1) ejection port cover.